Number of the day: 40401

Properties of the number 40401:

40401 = 3² × 67² is the 36164^th composite number and is not squarefree.
40401 has 2 distinct prime factors, 9 divisors, 18 antidivisors and 26532 totatives.
40401 = 201² is a perfect power of a semiprime.
40401 has a semiprime digit sum 9 in base 10.
40401 = 201² is a perfect square.
40401 = (200 × 201)/2 + (201 × 202)/2 is the sum of at least 2 consecutive triangular numbers in 1 way. In fact, it is the sum of 2 triangular numbers.
40401 = 20201² - 20200² = 6735² - 6732² = 2249² - 2240² = 335² - 268² = 201² - 0² is the difference of 2 nonnegative squares in 5 ways.
40401 is the difference of 2 positive pentagonal numbers in 1 way.
40401 is the sum of 3 positive squares.
40401² is the sum of 3 positive squares.
40401 is a proper divisor of 1471³³ - 1.
40401 is palindromic in (at least) the following bases: 66, -53, and -68.

The number 40401 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A017042: a(n) = (7*n + 5)^2.
A019544: Squares whose digits are squares.
A035090: Non-palindromic squares which when written backwards remain square (and still have the same number of digits).
A036896: Odd refactorable numbers.
A061457: Numbers n such that n and its reversal are both squares.
A062917: Nonpalindromic numbers n such that n is not divisible by 10 and n*R(n) is a square, where R(n) is the reversal of n (A004086).
A184095: T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with rows and columns in nondecreasing order and with no 2X2 subblock sum differing from a horizontal or vertical neighbor subblock sum by more than one
A202835: E.g.f.: exp(9*x/(1-2*x)) / sqrt(1-4*x^2).
A225873: Squares that become prime when their most significant (or leftmost) digit is removed.
A277948: Squares whose largest decimal digit is 4.