21057972256 has 48 divisors (see below), whose sum is σ = 42234605280. Its totient is φ = 10332352000.

The previous prime is 21057972241. The next prime is 21057972263. The reversal of 21057972256 is 65227975012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1098756 + ... + 1117756.

It is an arithmetic number, because the mean of its divisors is an integer number (879887610).

Almost surely, 2^21057972256 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 21057972256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21117302640).

21057972256 is an abundant number, since it is smaller than the sum of its proper divisors (21176633024).

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

21057972256 is a wasteful number, since it uses less digits than its factorization.

21057972256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19657 (or 19649 counting only the distinct ones).

The product of its (nonzero) digits is 529200, while the sum is 46.

The spelling of 21057972256 in words is "twenty-one billion, fifty-seven million, nine hundred seventy-two thousand, two hundred fifty-six".