664486561 has 2 divisors, whose sum is σ = 664486562. Its totient is φ = 664486560.

The previous prime is 664486513. The next prime is 664486567. The reversal of 664486561 is 165684466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 430977600 + 233508961 = 20760^2 + 15281^2 .

It is a cyclic number.

It is not a de Polignac number, because 664486561 - 2²⁵ = 630932129 is a prime.

It is not a weakly prime, because it can be changed into another prime (664486567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332243280 + 332243281.

It is an arithmetic number, because the mean of its divisors is an integer number (332243281).

Almost surely, 2^664486561 is an apocalyptic number.

It is an amenable number.

664486561 is a deficient number, since it is larger than the sum of its proper divisors (1).

664486561 is an equidigital number, since it uses as much as digits as its factorization.

664486561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 829440, while the sum is 46.

The square root of 664486561 is about 25777.6368389346. The cubic root of 664486561 is about 872.6271759841.

The spelling of 664486561 in words is "six hundred sixty-four million, four hundred eighty-six thousand, five hundred sixty-one".