190991991 has 8 divisors (see below), whose sum is σ = 269635824. Its totient is φ = 119838080.

The previous prime is 190991989. The next prime is 190991993. The reversal of 190991991 is 199199091.

It is an interprime number because it is at equal distance from previous prime (190991989) and next prime (190991993).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 190991991 - 2¹ = 190991989 is a prime.

It is a super-2 number, since 2×190991991² = 72955881252288162, 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 190991991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (190991993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1872420 + ... + 1872521.

It is an arithmetic number, because the mean of its divisors is an integer number (33704478).

Almost surely, 2^190991991 is an apocalyptic number.

190991991 is a deficient number, since it is larger than the sum of its proper divisors (78643833).

190991991 is a wasteful number, since it uses less digits than its factorization.

190991991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3744961.

The product of its (nonzero) digits is 59049, while the sum is 48.

The square root of 190991991 is about 13819.9852025970. The cubic root of 190991991 is about 575.8884724511. Note that the first 3 decimals are identical.

The spelling of 190991991 in words is "one hundred ninety million, nine hundred ninety-one thousand, nine hundred ninety-one".