189199991 has 2 divisors, whose sum is σ = 189199992. Its totient is φ = 189199990.

The previous prime is 189199951. The next prime is 189200003. The reversal of 189199991 is 199991981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 189199991 - 2²² = 185005687 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (189199921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94599995 + 94599996.

It is an arithmetic number, because the mean of its divisors is an integer number (94599996).

Almost surely, 2^189199991 is an apocalyptic number.

189199991 is a deficient number, since it is larger than the sum of its proper divisors (1).

189199991 is an equidigital number, since it uses as much as digits as its factorization.

189199991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 472392, while the sum is 56.

The square root of 189199991 is about 13754.9987640857. The cubic root of 189199991 is about 574.0817009484.

The spelling of 189199991 in words is "one hundred eighty-nine million, one hundred ninety-nine thousand, nine hundred ninety-one".