664402691 has 2 divisors, whose sum is σ = 664402692. Its totient is φ = 664402690.

The previous prime is 664402681. The next prime is 664402699. The reversal of 664402691 is 196204466.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 664402691 - 2²² = 660208387 is a prime.

It is not a weakly prime, because it can be changed into another prime (664402699) 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, 332201345 + 332201346.

It is an arithmetic number, because the mean of its divisors is an integer number (332201346).

Almost surely, 2^664402691 is an apocalyptic number.

664402691 is a deficient number, since it is larger than the sum of its proper divisors (1).

664402691 is an equidigital number, since it uses as much as digits as its factorization.

664402691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 62208, while the sum is 38.

The square root of 664402691 is about 25776.0099899112. The cubic root of 664402691 is about 872.5904607592.

The spelling of 664402691 in words is "six hundred sixty-four million, four hundred two thousand, six hundred ninety-one".