21392572644 has 81 divisors (see below), whose sum is σ = 57116069283. Its totient is φ = 6750283824.

The previous prime is 21392572639. The next prime is 21392572657. The reversal of 21392572644 is 44627529312.

The square root of 21392572644 is 146262.

It is a perfect power (a square), and thus also a powerful number.

21392572644 is a `hidden beast` number, since 2 + 1 + 39 + 2 + 572 + 6 + 44 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21392572644.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 16673227 + ... + 16674509.

Almost surely, 2^21392572644 is an apocalyptic number.

21392572644 is the 146262-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21392572644

21392572644 is an abundant number, since it is smaller than the sum of its proper divisors (35723496639).

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

21392572644 is a wasteful number, since it uses less digits than its factorization.

21392572644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2614 (or 1307 counting only the distinct ones).

The product of its digits is 725760, while the sum is 45.

The spelling of 21392572644 in words is "twenty-one billion, three hundred ninety-two million, five hundred seventy-two thousand, six hundred forty-four".