664445557 has 2 divisors, whose sum is σ = 664445558. Its totient is φ = 664445556.

The previous prime is 664445543. The next prime is 664445563. The reversal of 664445557 is 755544466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 414773956 + 249671601 = 20366^2 + 15801^2 .

It is a cyclic number.

It is not a de Polignac number, because 664445557 - 2⁷ = 664445429 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664445657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332222778 + 332222779.

It is an arithmetic number, because the mean of its divisors is an integer number (332222779).

Almost surely, 2^664445557 is an apocalyptic number.

It is an amenable number.

664445557 is a deficient number, since it is larger than the sum of its proper divisors (1).

664445557 is an equidigital number, since it uses as much as digits as its factorization.

664445557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016000, while the sum is 46.

The square root of 664445557 is about 25776.8414861092. The cubic root of 664445557 is about 872.6092263155.

The spelling of 664445557 in words is "six hundred sixty-four million, four hundred forty-five thousand, five hundred fifty-seven".