638723699 has 2 divisors, whose sum is σ = 638723700. Its totient is φ = 638723698.

The previous prime is 638723693. The next prime is 638723717. The reversal of 638723699 is 996327836.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638723699 - 2⁸ = 638723443 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638723699.

It is not a weakly prime, because it can be changed into another prime (638723693) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319361849 + 319361850.

It is an arithmetic number, because the mean of its divisors is an integer number (319361850).

Almost surely, 2^638723699 is an apocalyptic number.

638723699 is a deficient number, since it is larger than the sum of its proper divisors (1).

638723699 is an equidigital number, since it uses as much as digits as its factorization.

638723699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2939328, while the sum is 53.

The square root of 638723699 is about 25272.9835793086. The cubic root of 638723699 is about 861.2006391341.

The spelling of 638723699 in words is "six hundred thirty-eight million, seven hundred twenty-three thousand, six hundred ninety-nine".