664728457 has 2 divisors, whose sum is σ = 664728458. Its totient is φ = 664728456.

The previous prime is 664728439. The next prime is 664728461. The reversal of 664728457 is 754827466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 420619081 + 244109376 = 20509^2 + 15624^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664728457 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 664728457.

It is not a weakly prime, because it can be changed into another prime (664728557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332364228 + 332364229.

It is an arithmetic number, because the mean of its divisors is an integer number (332364229).

Almost surely, 2^664728457 is an apocalyptic number.

It is an amenable number.

664728457 is a deficient number, since it is larger than the sum of its proper divisors (1).

664728457 is an equidigital number, since it uses as much as digits as its factorization.

664728457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2257920, while the sum is 49.

The square root of 664728457 is about 25782.3283859313. The cubic root of 664728457 is about 872.7330519224.

Subtracting 664728457 from its reverse (754827466), we obtain a palindrome (90099009).

The spelling of 664728457 in words is "six hundred sixty-four million, seven hundred twenty-eight thousand, four hundred fifty-seven".