638401793 has 2 divisors, whose sum is σ = 638401794. Its totient is φ = 638401792.

The previous prime is 638401787. The next prime is 638401831. The reversal of 638401793 is 397104836.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 324828529 + 313573264 = 18023^2 + 17708^2 .

It is a cyclic number.

It is not a de Polignac number, because 638401793 - 2¹⁴ = 638385409 is a prime.

It is a super-2 number, since 2×638401793² = 815113698611229698, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 638401793.

It is not a weakly prime, because it can be changed into another prime (638401703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319200896 + 319200897.

It is an arithmetic number, because the mean of its divisors is an integer number (319200897).

Almost surely, 2^638401793 is an apocalyptic number.

It is an amenable number.

638401793 is a deficient number, since it is larger than the sum of its proper divisors (1).

638401793 is an equidigital number, since it uses as much as digits as its factorization.

638401793 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 41.

The square root of 638401793 is about 25266.6141973949. The cubic root of 638401793 is about 861.0559379439.

The spelling of 638401793 in words is "six hundred thirty-eight million, four hundred one thousand, seven hundred ninety-three".