644631629 has 2 divisors, whose sum is σ = 644631630. Its totient is φ = 644631628.

The previous prime is 644631623. The next prime is 644631641. The reversal of 644631629 is 926136446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 523036900 + 121594729 = 22870^2 + 11027^2 .

It is a cyclic number.

It is not a de Polignac number, because 644631629 - 2⁴ = 644631613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644631623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322315814 + 322315815.

It is an arithmetic number, because the mean of its divisors is an integer number (322315815).

Almost surely, 2^644631629 is an apocalyptic number.

It is an amenable number.

644631629 is a deficient number, since it is larger than the sum of its proper divisors (1).

644631629 is an equidigital number, since it uses as much as digits as its factorization.

644631629 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 41.

The square root of 644631629 is about 25389.5968656456. The cubic root of 644631629 is about 863.8477441791.

The spelling of 644631629 in words is "six hundred forty-four million, six hundred thirty-one thousand, six hundred twenty-nine".