20661615165 has 32 divisors (see below), whose sum is σ = 34215321600. Its totient is φ = 10635831360.

The previous prime is 20661615157. The next prime is 20661615167. The reversal of 20661615165 is 56151616602.

It is not a de Polignac number, because 20661615165 - 2³ = 20661615157 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661615167) 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, 117616 + ... + 234854.

It is an arithmetic number, because the mean of its divisors is an integer number (1069228800).

Almost surely, 2^20661615165 is an apocalyptic number.

It is an amenable number.

20661615165 is a deficient number, since it is larger than the sum of its proper divisors (13553706435).

20661615165 is a wasteful number, since it uses less digits than its factorization.

20661615165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117657.

The product of its (nonzero) digits is 64800, while the sum is 39.

The spelling of 20661615165 in words is "twenty billion, six hundred sixty-one million, six hundred fifteen thousand, one hundred sixty-five".