638342723 has 2 divisors, whose sum is σ = 638342724. Its totient is φ = 638342722.

The previous prime is 638342699. The next prime is 638342737. The reversal of 638342723 is 327243836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638342723 - 2⁶ = 638342659 is a prime.

It is not a weakly prime, because it can be changed into another prime (638342773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319171361 + 319171362.

It is an arithmetic number, because the mean of its divisors is an integer number (319171362).

Almost surely, 2^638342723 is an apocalyptic number.

638342723 is a deficient number, since it is larger than the sum of its proper divisors (1).

638342723 is an equidigital number, since it uses as much as digits as its factorization.

638342723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 38.

The square root of 638342723 is about 25265.4452365281. The cubic root of 638342723 is about 861.0293798819.

The spelling of 638342723 in words is "six hundred thirty-eight million, three hundred forty-two thousand, seven hundred twenty-three".