2165205897 has 20 divisors (see below), whose sum is σ = 3236965380. Its totient is φ = 1442345184.

The previous prime is 2165205871. The next prime is 2165205907. The reversal of 2165205897 is 7985025612.

2165205897 is a `hidden beast` number, since 2 + 1 + 65 + 2 + 0 + 589 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1640979081 + 524226816 = 40509^2 + 22896^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2165205897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2165205817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 101479 + ... + 120947.

It is an arithmetic number, because the mean of its divisors is an integer number (161848269).

Almost surely, 2^2165205897 is an apocalyptic number.

2165205897 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

2165205897 is a deficient number, since it is larger than the sum of its proper divisors (1071759483).

2165205897 is a wasteful number, since it uses less digits than its factorization.

2165205897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20854 (or 20845 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The square root of 2165205897 is about 46531.7729836292. The cubic root of 2165205897 is about 1293.6984775953.

The spelling of 2165205897 in words is "two billion, one hundred sixty-five million, two hundred five thousand, eight hundred ninety-seven".