644661031 has 8 divisors (see below), whose sum is σ = 753889664. Its totient is φ = 539715960.

The previous prime is 644661023. The next prime is 644661037. The reversal of 644661031 is 130166446.

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

It is not a de Polignac number, because 644661031 - 2³ = 644661023 is a prime.

It is a super-2 number, since 2×644661031² = 831175689779965922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644660984 and 644661002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644661037) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1070565 + ... + 1071166.

It is an arithmetic number, because the mean of its divisors is an integer number (94236208).

Almost surely, 2^644661031 is an apocalyptic number.

644661031 is a deficient number, since it is larger than the sum of its proper divisors (109228633).

644661031 is a wasteful number, since it uses less digits than its factorization.

644661031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2141781.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 644661031 is about 25390.1758757201. The cubic root of 644661031 is about 863.8608775016.

The spelling of 644661031 in words is "six hundred forty-four million, six hundred sixty-one thousand, thirty-one".