Number of the day: 763309

Richard Courant was born on this day 130 years ago.

Properties of the number 763309:

763309 is a cyclic number.
763309 = 29 × 26321 is semiprime and squarefree.
763309 has 2 distinct prime factors, 4 divisors, 15 antidivisors and 736960 totatives.
763309 has a triangular digit sum 28 in base 10.
Reversing the decimal digits of 763309 results in a prime.
763309 = 40³ + 44³ + 85³ is the sum of 3 positive cubes in 1 way.
763309 = 381655² - 381654² = 13175² - 13146² is the difference of 2 nonnegative squares in 2 ways.
763309 is the difference of 2 positive pentagonal numbers in 2 ways.
763309 = 422² + 765² = 222² + 845² is the sum of 2 positive squares in 2 ways.
763309 = 147² + 190² + 840² is the sum of 3 positive squares.
763309² = 407141² + 645660² = 186760² + 740109² = 375180² + 664741² = 526420² + 552741² is the sum of 2 positive squares in 4 ways.
763309² is the sum of 3 positive squares.
763309 is a proper divisor of 1291²⁸ - 1.
763309 = '763' + '309' is the concatenation of 2 semiprime numbers.
763309 is an emirpimes in (at least) the following bases: 4, 7, 8, 12, 13, 14, 16, 17, 19, 22, 25, 32, 37, 40, 41, 42, 49, 52, 53, 55, 63, 64, 69, 73, 74, 78, 79, 83, 85, 87, 89, 90, 91, 95, 96, and 97.

The number 763309 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequence (among others):

Sequence number and description below are taken from OEIS.
A202009: Number of -n..n circular arrays x(0..6) of 7 elements with zero sums of x(i) and x(i)*x((i+1) mod 7)