21564138407 has 8 divisors (see below), whose sum is σ = 25941820800. Its totient is φ = 17510728824.

The previous prime is 21564138371. The next prime is 21564138437. The reversal of 21564138407 is 70483146512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21564138407 - 2²⁴ = 21547361191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21564138437) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81068057 + ... + 81068322.

It is an arithmetic number, because the mean of its divisors is an integer number (3242727600).

Almost surely, 2^21564138407 is an apocalyptic number.

21564138407 is a deficient number, since it is larger than the sum of its proper divisors (4377682393).

21564138407 is a wasteful number, since it uses less digits than its factorization.

21564138407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162136405.

The product of its (nonzero) digits is 161280, while the sum is 41.

The spelling of 21564138407 in words is "twenty-one billion, five hundred sixty-four million, one hundred thirty-eight thousand, four hundred seven".