644072031 has 6 divisors (see below), whose sum is σ = 930326280. Its totient is φ = 429381348.

The previous prime is 644072021. The next prime is 644072063. The reversal of 644072031 is 130270446.

It is not a de Polignac number, because 644072031 - 2¹⁰ = 644071007 is a prime.

It is a super-2 number, since 2×644072031² = 829657562232929922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 644071986 and 644072004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644072021) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35781771 + ... + 35781788.

It is an arithmetic number, because the mean of its divisors is an integer number (155054380).

Almost surely, 2^644072031 is an apocalyptic number.

644072031 is a deficient number, since it is larger than the sum of its proper divisors (286254249).

644072031 is a wasteful number, since it uses less digits than its factorization.

644072031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71563565 (or 71563562 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 644072031 is about 25378.5742507336. The cubic root of 644072031 is about 863.5977060716.

The spelling of 644072031 in words is "six hundred forty-four million, seventy-two thousand, thirty-one".