21057557472 has 192 divisors, whose sum is σ = 70563225600. Its totient is φ = 5984616960.

The previous prime is 21057557449. The next prime is 21057557503. The reversal of 21057557472 is 27475575012.

21057557472 is a `hidden beast` number, since 2 + 1 + 0 + 5 + 7 + 5 + 574 + 72 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1146054 + ... + 1164282.

It is an arithmetic number, because the mean of its divisors is an integer number (367516800).

Almost surely, 2^21057557472 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 21057557472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35281612800).

21057557472 is an abundant number, since it is smaller than the sum of its proper divisors (49505668128).

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

21057557472 is a wasteful number, since it uses less digits than its factorization.

21057557472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18446 (or 18432 counting only the distinct ones).

The product of its (nonzero) digits is 686000, while the sum is 45.

The spelling of 21057557472 in words is "twenty-one billion, fifty-seven million, five hundred fifty-seven thousand, four hundred seventy-two".