21615156555 has 16 divisors (see below), whose sum is σ = 35058009120. Its totient is φ = 11370163968.

The previous prime is 21615156547. The next prime is 21615156587. The reversal of 21615156555 is 55565151612.

It is not a de Polignac number, because 21615156555 - 2³ = 21615156547 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9868840 + ... + 9871029.

It is an arithmetic number, because the mean of its divisors is an integer number (2191125570).

Almost surely, 2^21615156555 is an apocalyptic number.

21615156555 is a deficient number, since it is larger than the sum of its proper divisors (13442852565).

21615156555 is a wasteful number, since it uses less digits than its factorization.

21615156555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19739950.

The product of its digits is 225000, while the sum is 42.

The spelling of 21615156555 in words is "twenty-one billion, six hundred fifteen million, one hundred fifty-six thousand, five hundred fifty-five".