644242507 has 4 divisors (see below), whose sum is σ = 656398080. Its totient is φ = 632086936.

The previous prime is 644242499. The next prime is 644242513. The reversal of 644242507 is 705242446.

644242507 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 705242446 = 2 ⋅352621223.

It is a cyclic number.

It is not a de Polignac number, because 644242507 - 2³ = 644242499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644242517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6077707 + ... + 6077812.

It is an arithmetic number, because the mean of its divisors is an integer number (164099520).

Almost surely, 2^644242507 is an apocalyptic number.

644242507 is a deficient number, since it is larger than the sum of its proper divisors (12155573).

644242507 is a wasteful number, since it uses less digits than its factorization.

644242507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12155572.

The product of its (nonzero) digits is 53760, while the sum is 34.

The square root of 644242507 is about 25381.9326884302. The cubic root of 644242507 is about 863.6738930445.

The spelling of 644242507 in words is "six hundred forty-four million, two hundred forty-two thousand, five hundred seven".