664892581 has 2 divisors, whose sum is σ = 664892582. Its totient is φ = 664892580.

The previous prime is 664892561. The next prime is 664892623. The reversal of 664892581 is 185298466.

664892581 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 can be written as a sum of positive squares in only one way, i.e., 375041956 + 289850625 = 19366^2 + 17025^2 .

It is a cyclic number.

It is not a de Polignac number, because 664892581 - 2⁷ = 664892453 is a prime.

It is a super-2 number, since 2×664892581² = 884164288537683122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664892521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332446290 + 332446291.

It is an arithmetic number, because the mean of its divisors is an integer number (332446291).

Almost surely, 2^664892581 is an apocalyptic number.

It is an amenable number.

664892581 is a deficient number, since it is larger than the sum of its proper divisors (1).

664892581 is an equidigital number, since it uses as much as digits as its factorization.

664892581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 829440, while the sum is 49.

The square root of 664892581 is about 25785.5110672641. The cubic root of 664892581 is about 872.8048730553.

The spelling of 664892581 in words is "six hundred sixty-four million, eight hundred ninety-two thousand, five hundred eighty-one".