645904168091 has 16 divisors (see below), whose sum is σ = 829522412544. Its totient is φ = 488825704224.

The previous prime is 645904168087. The next prime is 645904168099. The reversal of 645904168091 is 190861409546.

It is not a de Polignac number, because 645904168091 - 2² = 645904168087 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645904168099) 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, 154298951 + ... + 154303136.

It is an arithmetic number, because the mean of its divisors is an integer number (51845150784).

Almost surely, 2^645904168091 is an apocalyptic number.

645904168091 is a deficient number, since it is larger than the sum of its proper divisors (183618244453).

645904168091 is a wasteful number, since it uses less digits than its factorization.

645904168091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308602130.

The product of its (nonzero) digits is 1866240, while the sum is 53.

The spelling of 645904168091 in words is "six hundred forty-five billion, nine hundred four million, one hundred sixty-eight thousand, ninety-one".