191989915 has 12 divisors (see below), whose sum is σ = 249474384. Its totient is φ = 141776544.

The previous prime is 191989909. The next prime is 191989933. The reversal of 191989915 is 519989191.

191989915 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-191989915 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 112759 + ... + 114448.

It is an arithmetic number, because the mean of its divisors is an integer number (20789532).

Almost surely, 2^191989915 is an apocalyptic number.

191989915 is a deficient number, since it is larger than the sum of its proper divisors (57484469).

191989915 is a wasteful number, since it uses less digits than its factorization.

191989915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227238 (or 227225 counting only the distinct ones).

The product of its digits is 262440, while the sum is 52.

The square root of 191989915 is about 13856.0425446806. The cubic root of 191989915 is about 576.8897271913.

The spelling of 191989915 in words is "one hundred ninety-one million, nine hundred eighty-nine thousand, nine hundred fifteen".