2161055661265 has 16 divisors (see below), whose sum is σ = 2668117772880. Its totient is φ = 1679312148480.

The previous prime is 2161055661263. The next prime is 2161055661283. The reversal of 2161055661265 is 5621665501612.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 287683122321 + 1873372538944 = 536361^2 + 1368712^2 .

It is not a de Polignac number, because 2161055661265 - 2¹ = 2161055661263 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2161055661263) 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, 22969944 + ... + 23063833.

It is an arithmetic number, because the mean of its divisors is an integer number (166757360805).

Almost surely, 2^{2161055661265} is an apocalyptic number.

It is an amenable number.

2161055661265 is a deficient number, since it is larger than the sum of its proper divisors (507062111615).

2161055661265 is a wasteful number, since it uses less digits than its factorization.

2161055661265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46034052.

The product of its (nonzero) digits is 648000, while the sum is 46.

The spelling of 2161055661265 in words is "two trillion, one hundred sixty-one billion, fifty-five million, six hundred sixty-one thousand, two hundred sixty-five".