21564465723 has 6 divisors (see below), whose sum is σ = 31148672724. Its totient is φ = 14376310476.

The previous prime is 21564465673. The next prime is 21564465733. The reversal of 21564465723 is 32756446512.

21564465723 is a `hidden beast` number, since 2 + 1 + 564 + 4 + 65 + 7 + 23 = 666.

It is not a de Polignac number, because 21564465723 - 2¹⁸ = 21564203579 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21564465733) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1198025865 + ... + 1198025882.

It is an arithmetic number, because the mean of its divisors is an integer number (5191445454).

Almost surely, 2^21564465723 is an apocalyptic number.

21564465723 is a deficient number, since it is larger than the sum of its proper divisors (9584207001).

21564465723 is a wasteful number, since it uses less digits than its factorization.

21564465723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2396051753 (or 2396051750 counting only the distinct ones).

The product of its digits is 1209600, while the sum is 45.

The spelling of 21564465723 in words is "twenty-one billion, five hundred sixty-four million, four hundred sixty-five thousand, seven hundred twenty-three".