191981989 has 8 divisors (see below), whose sum is σ = 202582080. Its totient is φ = 181569696.

The previous prime is 191981957. The next prime is 191982019. The reversal of 191981989 is 989189191.

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 191981989 - 2⁵ = 191981957 is a prime.

It is a super-2 number, since 2×191981989² = 73714168200792242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191981939) 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, 44847 + ... + 48940.

It is an arithmetic number, because the mean of its divisors is an integer number (25322760).

Almost surely, 2^191981989 is an apocalyptic number.

It is an amenable number.

191981989 is a deficient number, since it is larger than the sum of its proper divisors (10600091).

191981989 is an equidigital number, since it uses as much as digits as its factorization.

191981989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93899.

The product of its digits is 419904, while the sum is 55.

The square root of 191981989 is about 13855.7565293274. The cubic root of 191981989 is about 576.8817884221.

The spelling of 191981989 in words is "one hundred ninety-one million, nine hundred eighty-one thousand, nine hundred eighty-nine".