644215057 has 2 divisors, whose sum is σ = 644215058. Its totient is φ = 644215056.

The previous prime is 644215049. The next prime is 644215063. The reversal of 644215057 is 750512446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 536802561 + 107412496 = 23169^2 + 10364^2 .

It is a cyclic number.

It is not a de Polignac number, because 644215057 - 2³ = 644215049 is a prime.

It is not a weakly prime, because it can be changed into another prime (644215037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322107528 + 322107529.

It is an arithmetic number, because the mean of its divisors is an integer number (322107529).

Almost surely, 2^644215057 is an apocalyptic number.

It is an amenable number.

644215057 is a deficient number, since it is larger than the sum of its proper divisors (1).

644215057 is an equidigital number, since it uses as much as digits as its factorization.

644215057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 33600, while the sum is 34.

The square root of 644215057 is about 25381.3919437055. The cubic root of 644215057 is about 863.6616263464.

The spelling of 644215057 in words is "six hundred forty-four million, two hundred fifteen thousand, fifty-seven".