638198831 has 2 divisors, whose sum is σ = 638198832. Its totient is φ = 638198830.

The previous prime is 638198791. The next prime is 638198833. The reversal of 638198831 is 138891836.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638198831 is a prime.

It is a super-2 number, since 2×638198831² = 814595495779533122, which contains 22 as substring.

Together with 638198833, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638198833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319099415 + 319099416.

It is an arithmetic number, because the mean of its divisors is an integer number (319099416).

Almost surely, 2^638198831 is an apocalyptic number.

638198831 is a deficient number, since it is larger than the sum of its proper divisors (1).

638198831 is an equidigital number, since it uses as much as digits as its factorization.

638198831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 47.

The square root of 638198831 is about 25262.5974713607. The cubic root of 638198831 is about 860.9646787188.

The spelling of 638198831 in words is "six hundred thirty-eight million, one hundred ninety-eight thousand, eight hundred thirty-one".