664236817 has 2 divisors, whose sum is σ = 664236818. Its totient is φ = 664236816.

The previous prime is 664236779. The next prime is 664236829. The reversal of 664236817 is 718632466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 575952001 + 88284816 = 23999^2 + 9396^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664236817 is a prime.

It is not a weakly prime, because it can be changed into another prime (664236857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332118408 + 332118409.

It is an arithmetic number, because the mean of its divisors is an integer number (332118409).

Almost surely, 2^664236817 is an apocalyptic number.

It is an amenable number.

664236817 is a deficient number, since it is larger than the sum of its proper divisors (1).

664236817 is an equidigital number, since it uses as much as digits as its factorization.

664236817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 43.

The square root of 664236817 is about 25772.7921847828. The cubic root of 664236817 is about 872.5178380767.

The spelling of 664236817 in words is "six hundred sixty-four million, two hundred thirty-six thousand, eight hundred seventeen".