644600406600 has 72 divisors (see below), whose sum is σ = 2164783038210. Its totient is φ = 171893441280.

The previous prime is 644600406599. The next prime is 644600406623. The reversal of 644600406600 is 6604006446.

It is a happy number.

644600406600 is a `hidden beast` number, since 6 + 4 + 4 + 6 + 0 + 0 + 40 + 6 + 600 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 563931910116 + 80668496484 = 750954^2 + 284022^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 179053869 + ... + 179057468.

Almost surely, 2^644600406600 is an apocalyptic number.

644600406600 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

644600406600 is an abundant number, since it is smaller than the sum of its proper divisors (1520182631610).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644600406600 is a wasteful number, since it uses less digits than its factorization.

644600406600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358111359 (or 358111347 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The spelling of 644600406600 in words is "six hundred forty-four billion, six hundred million, four hundred six thousand, six hundred".