Number of the day: 768721

Properties of the number 768721:

768721 is a cyclic number.
768721 = 19 × 40459 is semiprime and squarefree.
768721 has 2 distinct prime factors, 4 divisors, 7 antidivisors and 728244 totatives.
768721 has an emirp digit sum 31 in base 10.
Reversing the decimal digits of 768721 results in a prime.
768721 = 384361² - 384360² = 20239² - 20220² is the difference of 2 nonnegative squares in 2 ways.
768721 is the difference of 2 positive pentagonal numbers in 2 ways.
768721 = 61² + 90² + 870² is the sum of 3 positive squares.
768721² is the sum of 3 positive squares.
768721 is a proper divisor of 1861⁶⁶ - 1.
768721 is an emirpimes in (at least) the following bases: 3, 4, 5, 9, 17, 19, 28, 33, 34, 35, 41, 43, 45, 51, 52, 53, 55, 61, 62, 65, 69, 71, 73, 74, 75, 79, 84, 89, 90, 91, 93, and 97.
768721 in base 3 = 1110001111011 and consists of only the digits '0' and '1'.

The number 768721 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequence (among others):

Sequence number and description below are taken from OEIS.
A245157: G.f.: Sum_{n>=0} x^n/((1+x)^(2*n+1)*(1 - (2*n+1)*x)).