199951931 has 2 divisors, whose sum is σ = 199951932. Its totient is φ = 199951930.

The previous prime is 199951907. The next prime is 199951933. The reversal of 199951931 is 139159991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 199951931 - 2⁶ = 199951867 is a prime.

It is a super-2 number, since 2×199951931² = 79961549421257522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 199951933, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (199951933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99975965 + 99975966.

It is an arithmetic number, because the mean of its divisors is an integer number (99975966).

Almost surely, 2^199951931 is an apocalyptic number.

199951931 is a deficient number, since it is larger than the sum of its proper divisors (1).

199951931 is an equidigital number, since it uses as much as digits as its factorization.

199951931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 98415, while the sum is 47.

The square root of 199951931 is about 14140.4360258091. The cubic root of 199951931 is about 584.7566923523.

The spelling of 199951931 in words is "one hundred ninety-nine million, nine hundred fifty-one thousand, nine hundred thirty-one".