21565256512 has 14 divisors (see below), whose sum is σ = 42793556018. Its totient is φ = 10782628224.

The previous prime is 21565256509. The next prime is 21565256521.

21565256512 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 13193738496 + 8371518016 = 114864^2 + 91496^2 .

It is a super-2 number, since 2×21565256512² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 168478503 + ... + 168478630.

Almost surely, 2^21565256512 is an apocalyptic number.

It is an amenable number.

21565256512 is a deficient number, since it is larger than the sum of its proper divisors (21228299506).

21565256512 is an equidigital number, since it uses as much as digits as its factorization.

21565256512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336957145 (or 336957135 counting only the distinct ones).

The product of its digits is 180000, while the sum is 40.

The spelling of 21565256512 in words is "twenty-one billion, five hundred sixty-five million, two hundred fifty-six thousand, five hundred twelve".