199931 has 2 divisors, whose sum is σ = 199932. Its totient is φ = 199930.

The previous prime is 199921. The next prime is 199933. The reversal of 199931 is 139991.

It is a strong prime.

It is an emirp because it is prime and its reverse (139991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199931 is a prime.

It is a super-2 number, since 2×199931² = 79944809522, which contains 22 as substring.

Together with 199933, 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 (199933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99965 + 99966.

It is an arithmetic number, because the mean of its divisors is an integer number (99966).

2¹⁹⁹⁹³¹ is an apocalyptic number.

199931 is a deficient number, since it is larger than the sum of its proper divisors (1).

199931 is an equidigital number, since it uses as much as digits as its factorization.

199931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2187, while the sum is 32.

The square root of 199931 is about 447.1364444999. The cubic root of 199931 is about 58.4736287499.

The spelling of 199931 in words is "one hundred ninety-nine thousand, nine hundred thirty-one".