21009632256 has 264 divisors, whose sum is σ = 65664877824. Its totient is φ = 6696898560.

The previous prime is 21009632243. The next prime is 21009632269. The reversal of 21009632256 is 65223690012.

21009632256 is a `hidden beast` number, since 2 + 10 + 0 + 9 + 632 + 2 + 5 + 6 = 666.

It is an interprime number because it is at equal distance from previous prime (21009632243) and next prime (21009632269).

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 21009632256.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5721301 + ... + 5724971.

Almost surely, 2^21009632256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21009632256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32832438912).

21009632256 is an abundant number, since it is smaller than the sum of its proper divisors (44655245568).

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

21009632256 is an equidigital number, since it uses as much as digits as its factorization.

21009632256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3729 (or 3699 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The spelling of 21009632256 in words is "twenty-one billion, nine million, six hundred thirty-two thousand, two hundred fifty-six".