21564764515 has 24 divisors (see below), whose sum is σ = 31073715072. Its totient is φ = 14310253440.

The previous prime is 21564764489. The next prime is 21564764521. The reversal of 21564764515 is 51546746512.

It is not a de Polignac number, because 21564764515 - 2¹¹ = 21564762467 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1412074 + ... + 1427263.

It is an arithmetic number, because the mean of its divisors is an integer number (1294738128).

Almost surely, 2^21564764515 is an apocalyptic number.

21564764515 is a deficient number, since it is larger than the sum of its proper divisors (9508950557).

21564764515 is a wasteful number, since it uses less digits than its factorization.

21564764515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2839387 (or 2839380 counting only the distinct ones).

The product of its digits is 1008000, while the sum is 46.

The spelling of 21564764515 in words is "twenty-one billion, five hundred sixty-four million, seven hundred sixty-four thousand, five hundred fifteen".