21013645356 has 72 divisors (see below), whose sum is σ = 58762948608. Its totient is φ = 6278076000.

The previous prime is 21013645313. The next prime is 21013645391. The reversal of 21013645356 is 65354631012.

21013645356 is a `hidden beast` number, since 2 + 1 + 0 + 1 + 3 + 645 + 3 + 5 + 6 = 666.

It is a super-2 number, since 2×21013645356² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21013645356.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 345580 + ... + 401811.

It is an arithmetic number, because the mean of its divisors is an integer number (816152064).

Almost surely, 2^21013645356 is an apocalyptic number.

It is an amenable number.

21013645356 is an abundant number, since it is smaller than the sum of its proper divisors (37749303252).

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

21013645356 is a wasteful number, since it uses less digits than its factorization.

21013645356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 747483 (or 747478 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 36.

The spelling of 21013645356 in words is "twenty-one billion, thirteen million, six hundred forty-five thousand, three hundred fifty-six".