191987939 has 8 divisors (see below), whose sum is σ = 225552432. Its totient is φ = 161108640.

The previous prime is 191987927. The next prime is 191987941. The reversal of 191987939 is 939789191.

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

It is not a de Polignac number, because 191987939 - 2²⁰ = 190939363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191987909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 671144 + ... + 671429.

It is an arithmetic number, because the mean of its divisors is an integer number (28194054).

Almost surely, 2^191987939 is an apocalyptic number.

191987939 is a deficient number, since it is larger than the sum of its proper divisors (33564493).

191987939 is a wasteful number, since it uses less digits than its factorization.

191987939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1342597.

The product of its digits is 1102248, while the sum is 56.

The square root of 191987939 is about 13855.9712398662. The cubic root of 191987939 is about 576.8877480283.

The spelling of 191987939 in words is "one hundred ninety-one million, nine hundred eighty-seven thousand, nine hundred thirty-nine".