644165001 has 32 divisors (see below), whose sum is σ = 979689600. Its totient is φ = 418176000.

The previous prime is 644164967. The next prime is 644165017. The reversal of 644165001 is 100561446.

644165001 is a `hidden beast` number, since 6 + 4 + 4 + 1 + 650 + 0 + 1 = 666.

It is not a de Polignac number, because 644165001 - 2²⁵ = 610610569 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (644165051) 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, 159001 + ... + 163001.

It is an arithmetic number, because the mean of its divisors is an integer number (30615300).

Almost surely, 2^644165001 is an apocalyptic number.

It is an amenable number.

644165001 is a deficient number, since it is larger than the sum of its proper divisors (335524599).

644165001 is a wasteful number, since it uses less digits than its factorization.

644165001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4166 (or 4160 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 644165001 is about 25380.4058478189. The cubic root of 644165001 is about 863.6392567119.

The spelling of 644165001 in words is "six hundred forty-four million, one hundred sixty-five thousand, one".