638323913 has 2 divisors, whose sum is σ = 638323914. Its totient is φ = 638323912.

The previous prime is 638323909. The next prime is 638323919. The reversal of 638323913 is 319323836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 485232784 + 153091129 = 22028^2 + 12373^2 .

It is a cyclic number.

It is not a de Polignac number, because 638323913 - 2² = 638323909 is a prime.

It is not a weakly prime, because it can be changed into another prime (638323919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319161956 + 319161957.

It is an arithmetic number, because the mean of its divisors is an integer number (319161957).

Almost surely, 2^638323913 is an apocalyptic number.

It is an amenable number.

638323913 is a deficient number, since it is larger than the sum of its proper divisors (1).

638323913 is an equidigital number, since it uses as much as digits as its factorization.

638323913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69984, while the sum is 38.

The square root of 638323913 is about 25265.0729862393. The cubic root of 638323913 is about 861.0209225015.

The spelling of 638323913 in words is "six hundred thirty-eight million, three hundred twenty-three thousand, nine hundred thirteen".