644507 has 2 divisors, whose sum is σ = 644508. Its totient is φ = 644506.

The previous prime is 644491. The next prime is 644513. The reversal of 644507 is 705446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644507 - 2⁴ = 644491 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322253 + 322254.

It is an arithmetic number, because the mean of its divisors is an integer number (322254).

2⁶⁴⁴⁵⁰⁷ is an apocalyptic number.

644507 is a deficient number, since it is larger than the sum of its proper divisors (1).

644507 is an equidigital number, since it uses as much as digits as its factorization.

644507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 644507 is about 802.8119331450. The cubic root of 644507 is about 86.3792070306.

The spelling of 644507 in words is "six hundred forty-four thousand, five hundred seven".