21321500565 has 16 divisors (see below), whose sum is σ = 34146579456. Its totient is φ = 11360740800.

The previous prime is 21321500533. The next prime is 21321500569. The reversal of 21321500565 is 56500512312.

It is a happy number.

It is not a de Polignac number, because 21321500565 - 2⁵ = 21321500533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321500569) 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, 653941 + ... + 685770.

It is an arithmetic number, because the mean of its divisors is an integer number (2134161216).

Almost surely, 2^21321500565 is an apocalyptic number.

It is an amenable number.

21321500565 is a deficient number, since it is larger than the sum of its proper divisors (12825078891).

21321500565 is a wasteful number, since it uses less digits than its factorization.

21321500565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1340780.

The product of its (nonzero) digits is 9000, while the sum is 30.

The spelling of 21321500565 in words is "twenty-one billion, three hundred twenty-one million, five hundred thousand, five hundred sixty-five".