21565056567 has 16 divisors (see below), whose sum is σ = 28800368640. Its totient is φ = 14353248672.

The previous prime is 21565056533. The next prime is 21565056571. The reversal of 21565056567 is 76565056512.

It is a happy number.

It is not a de Polignac number, because 21565056567 - 2⁶ = 21565056503 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21565056967) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8006473 + ... + 8009165.

It is an arithmetic number, because the mean of its divisors is an integer number (1800023040).

Almost surely, 2^21565056567 is an apocalyptic number.

21565056567 is a deficient number, since it is larger than the sum of its proper divisors (7235312073).

21565056567 is a wasteful number, since it uses less digits than its factorization.

21565056567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6062.

The product of its (nonzero) digits is 1890000, while the sum is 48.

Subtracting 21565056567 from its reverse (76565056512), we obtain a palindrome (54999999945).

The spelling of 21565056567 in words is "twenty-one billion, five hundred sixty-five million, fifty-six thousand, five hundred sixty-seven".