2165615565021 has 12 divisors (see below), whose sum is σ = 3128137102272. Its totient is φ = 1443731834376.

The previous prime is 2165615564993. The next prime is 2165615565023. The reversal of 2165615565021 is 1205655165612.

It is a happy number.

2165615565021 is a `hidden beast` number, since 2 + 1 + 6 + 5 + 61 + 5 + 565 + 0 + 21 = 666.

It is not a de Polignac number, because 2165615565021 - 2¹¹ = 2165615562973 is a prime.

It is a super-2 number, since 2×2165615565021² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2165615565023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 246570 + ... + 2095716.

It is an arithmetic number, because the mean of its divisors is an integer number (260678091856).

Almost surely, 2^{2165615565021} is an apocalyptic number.

It is an amenable number.

2165615565021 is a deficient number, since it is larger than the sum of its proper divisors (962521537251).

2165615565021 is a wasteful number, since it uses less digits than its factorization.

2165615565021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1979280 (or 1979277 counting only the distinct ones).

The product of its (nonzero) digits is 540000, while the sum is 45.

The spelling of 2165615565021 in words is "two trillion, one hundred sixty-five billion, six hundred fifteen million, five hundred sixty-five thousand, twenty-one".