644800500977 has 16 divisors (see below), whose sum is σ = 649221460560. Its totient is φ = 640399269888.

The previous prime is 644800500959. The next prime is 644800500983. The reversal of 644800500977 is 779005008446.

It can be written as a sum of positive squares in 8 ways, for example, as 434680801 + 644365820176 = 20849^2 + 802724^2 .

It is a cyclic number.

It is not a de Polignac number, because 644800500977 - 2⁶ = 644800500913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644800500937) 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, 101877149 + ... + 101883477.

It is an arithmetic number, because the mean of its divisors is an integer number (40576341285).

Almost surely, 2^644800500977 is an apocalyptic number.

It is an amenable number.

644800500977 is a deficient number, since it is larger than the sum of its proper divisors (4420959583).

644800500977 is a wasteful number, since it uses less digits than its factorization.

644800500977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7780.

The product of its (nonzero) digits is 1693440, while the sum is 50.

The spelling of 644800500977 in words is "six hundred forty-four billion, eight hundred million, five hundred thousand, nine hundred seventy-seven".