21657315072 has 288 divisors, whose sum is σ = 63870912000. Its totient is φ = 6487326720.

The previous prime is 21657315061. The next prime is 21657315089. The reversal of 21657315072 is 27051375612.

It is a happy number.

It is a super-2 number, since 2×21657315072² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21657315072.

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, 25812829 + ... + 25813667.

It is an arithmetic number, because the mean of its divisors is an integer number (221774000).

Almost surely, 2^21657315072 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 21657315072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31935456000).

21657315072 is an abundant number, since it is smaller than the sum of its proper divisors (42213596928).

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

21657315072 is a wasteful number, since it uses less digits than its factorization.

21657315072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 967 (or 953 counting only the distinct ones).

The product of its (nonzero) digits is 88200, while the sum is 39.

The spelling of 21657315072 in words is "twenty-one billion, six hundred fifty-seven million, three hundred fifteen thousand, seventy-two".