21566766252 has 12 divisors (see below), whose sum is σ = 50322454616. Its totient is φ = 7188922080.

The previous prime is 21566766233. The next prime is 21566766257. The reversal of 21566766252 is 25266766512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21566766252² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21566766257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 898615249 + ... + 898615272.

Almost surely, 2^21566766252 is an apocalyptic number.

It is an amenable number.

21566766252 is an abundant number, since it is smaller than the sum of its proper divisors (28755688364).

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

21566766252 is a wasteful number, since it uses less digits than its factorization.

21566766252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1797230528 (or 1797230526 counting only the distinct ones).

The product of its digits is 1814400, while the sum is 48.

The spelling of 21566766252 in words is "twenty-one billion, five hundred sixty-six million, seven hundred sixty-six thousand, two hundred fifty-two".