21021828564 has 24 divisors (see below), whose sum is σ = 53510109408. Its totient is φ = 6370251040.

The previous prime is 21021828563. The next prime is 21021828577. The reversal of 21021828564 is 46582812012.

21021828564 = T₆₈₃₄₄ + T₆₈₃₄₅ + ... + T₆₈₃₅₂.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021828563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79628007 + ... + 79628270.

It is an arithmetic number, because the mean of its divisors is an integer number (2229587892).

Almost surely, 2^21021828564 is an apocalyptic number.

It is an amenable number.

21021828564 is an abundant number, since it is smaller than the sum of its proper divisors (32488280844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21021828564 is a wasteful number, since it uses less digits than its factorization.

21021828564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159256295 (or 159256293 counting only the distinct ones).

The product of its (nonzero) digits is 61440, while the sum is 39.

The spelling of 21021828564 in words is "twenty-one billion, twenty-one million, eight hundred twenty-eight thousand, five hundred sixty-four".