644613239 has 2 divisors, whose sum is σ = 644613240. Its totient is φ = 644613238.

The previous prime is 644613227. The next prime is 644613241. The reversal of 644613239 is 932316446.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644613239 - 2¹⁶ = 644547703 is a prime.

It is a super-2 number, since 2×644613239² = 831052455788142242, which contains 22 as substring.

Together with 644613241, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644613539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322306619 + 322306620.

It is an arithmetic number, because the mean of its divisors is an integer number (322306620).

Almost surely, 2^644613239 is an apocalyptic number.

644613239 is a deficient number, since it is larger than the sum of its proper divisors (1).

644613239 is an equidigital number, since it uses as much as digits as its factorization.

644613239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 38.

The square root of 644613239 is about 25389.2347068595. The cubic root of 644613239 is about 863.8395295077.

The spelling of 644613239 in words is "six hundred forty-four million, six hundred thirteen thousand, two hundred thirty-nine".