644880939 has 8 divisors (see below), whose sum is σ = 861017232. Its totient is φ = 429332640.

The previous prime is 644880889. The next prime is 644880953. The reversal of 644880939 is 939088446.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644880939 - 2⁷ = 644880811 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644880891 and 644880900.

It is not an unprimeable number, because it can be changed into a prime (644882939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 144432 + ... + 148829.

It is an arithmetic number, because the mean of its divisors is an integer number (107627154).

Almost surely, 2^644880939 is an apocalyptic number.

644880939 is a deficient number, since it is larger than the sum of its proper divisors (216136293).

644880939 is a wasteful number, since it uses less digits than its factorization.

644880939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293997.

The product of its (nonzero) digits is 1492992, while the sum is 51.

The square root of 644880939 is about 25394.5060790715. The cubic root of 644880939 is about 863.9590936244.

The spelling of 644880939 in words is "six hundred forty-four million, eight hundred eighty thousand, nine hundred thirty-nine".