644660231 has 2 divisors, whose sum is σ = 644660232. Its totient is φ = 644660230.

The previous prime is 644660209. The next prime is 644660309. The reversal of 644660231 is 132066446.

644660231 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644660231 - 2⁶ = 644660167 is a prime.

It is a super-2 number, since 2×644660231² = 831173626865946722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644660201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322330115 + 322330116.

It is an arithmetic number, because the mean of its divisors is an integer number (322330116).

Almost surely, 2^644660231 is an apocalyptic number.

644660231 is a deficient number, since it is larger than the sum of its proper divisors (1).

644660231 is an equidigital number, since it uses as much as digits as its factorization.

644660231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 32.

The square root of 644660231 is about 25390.1601215904. The cubic root of 644660231 is about 863.8605201619.

The spelling of 644660231 in words is "six hundred forty-four million, six hundred sixty thousand, two hundred thirty-one".