21672550656 has 81 divisors (see below), whose sum is σ = 62507687151. Its totient is φ = 7221828096.

The previous prime is 21672550643. The next prime is 21672550673. The reversal of 21672550656 is 65605527612.

The square root of 21672550656 is 147216.

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

21672550656 is a `hidden beast` number, since 21 + 6 + 72 + 5 + 506 + 56 = 666.

It is a super-4 number, since 4×21672550656⁴ (a number of 42 digits) contains 4444 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 7064835 + ... + 7067901.

Almost surely, 2^21672550656 is an apocalyptic number.

21672550656 is the 147216-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21672550656

21672550656 is an abundant number, since it is smaller than the sum of its proper divisors (40835136495).

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

21672550656 is an frugal number, since it uses more digits than its factorization.

21672550656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6156 (or 3072 counting only the distinct ones).

The product of its (nonzero) digits is 756000, while the sum is 45.

The spelling of 21672550656 in words is "twenty-one billion, six hundred seventy-two million, five hundred fifty thousand, six hundred fifty-six".