664985801 has 2 divisors, whose sum is σ = 664985802. Its totient is φ = 664985800.

The previous prime is 664985773. The next prime is 664985809. The reversal of 664985801 is 108589466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 645414025 + 19571776 = 25405^2 + 4424^2 .

It is a cyclic number.

It is not a de Polignac number, because 664985801 - 2²² = 660791497 is a prime.

It is a super-2 number, since 2×664985801² = 884412231063223202, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (664985809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332492900 + 332492901.

It is an arithmetic number, because the mean of its divisors is an integer number (332492901).

Almost surely, 2^664985801 is an apocalyptic number.

It is an amenable number.

664985801 is a deficient number, since it is larger than the sum of its proper divisors (1).

664985801 is an equidigital number, since it uses as much as digits as its factorization.

664985801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 414720, while the sum is 47.

The square root of 664985801 is about 25787.3186081841. The cubic root of 664985801 is about 872.8456611317.

The spelling of 664985801 in words is "six hundred sixty-four million, nine hundred eighty-five thousand, eight hundred one".