21065522256 has 560 divisors, whose sum is σ = 70259788800. Its totient is φ = 6076477440.

The previous prime is 21065522237. The next prime is 21065522323. The reversal of 21065522256 is 65222556012.

21065522256 is a `hidden beast` number, since 2 + 106 + 5 + 522 + 25 + 6 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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 21065522256.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 141379270 + ... + 141379418.

Almost surely, 2^21065522256 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 21065522256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35129894400).

21065522256 is an abundant number, since it is smaller than the sum of its proper divisors (49194266544).

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

21065522256 is a wasteful number, since it uses less digits than its factorization.

21065522256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 36.

The spelling of 21065522256 in words is "twenty-one billion, sixty-five million, five hundred twenty-two thousand, two hundred fifty-six".