21501513165 has 32 divisors (see below), whose sum is σ = 37894311936. Its totient is φ = 10323754560.

The previous prime is 21501513161. The next prime is 21501513199. The reversal of 21501513165 is 56131510512.

It is not a de Polignac number, because 21501513165 - 2² = 21501513161 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21501513161) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 615589 + ... + 649578.

It is an arithmetic number, because the mean of its divisors is an integer number (1184197248).

Almost surely, 2^21501513165 is an apocalyptic number.

It is an amenable number.

21501513165 is a deficient number, since it is larger than the sum of its proper divisors (16392798771).

21501513165 is a wasteful number, since it uses less digits than its factorization.

21501513165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1265289.

The product of its (nonzero) digits is 4500, while the sum is 30.

The spelling of 21501513165 in words is "twenty-one billion, five hundred one million, five hundred thirteen thousand, one hundred sixty-five".