644932375939 has 4 divisors (see below), whose sum is σ = 646471594440. Its totient is φ = 643393157440.

The previous prime is 644932375933. The next prime is 644932375943. The reversal of 644932375939 is 939573239446.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 644932375939 - 2¹⁹ = 644931851651 is a prime.

It is a super-2 number, since 2×644932375939² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644932375933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 769608622 + ... + 769609459.

It is an arithmetic number, because the mean of its divisors is an integer number (161617898610).

Almost surely, 2^644932375939 is an apocalyptic number.

644932375939 is a deficient number, since it is larger than the sum of its proper divisors (1539218501).

644932375939 is a wasteful number, since it uses less digits than its factorization.

644932375939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1539218500.

The product of its digits is 132269760, while the sum is 64.

The spelling of 644932375939 in words is "six hundred forty-four billion, nine hundred thirty-two million, three hundred seventy-five thousand, nine hundred thirty-nine".