664194637 has 2 divisors, whose sum is σ = 664194638. Its totient is φ = 664194636.

The previous prime is 664194617. The next prime is 664194649. The reversal of 664194637 is 736491466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 342028036 + 322166601 = 18494^2 + 17949^2 .

It is a cyclic number.

It is not a de Polignac number, because 664194637 - 2¹¹ = 664192589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664194617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332097318 + 332097319.

It is an arithmetic number, because the mean of its divisors is an integer number (332097319).

Almost surely, 2^664194637 is an apocalyptic number.

It is an amenable number.

664194637 is a deficient number, since it is larger than the sum of its proper divisors (1).

664194637 is an equidigital number, since it uses as much as digits as its factorization.

664194637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 46.

The square root of 664194637 is about 25771.9738669742. The cubic root of 664194637 is about 872.4993689702.

The spelling of 664194637 in words is "six hundred sixty-four million, one hundred ninety-four thousand, six hundred thirty-seven".