191981388 has 48 divisors (see below), whose sum is σ = 465905664. Its totient is φ = 61461120.

The previous prime is 191981381. The next prime is 191981389. The reversal of 191981388 is 883189191.

It is not an unprimeable number, because it can be changed into a prime (191981381) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49081 + ... + 52847.

It is an arithmetic number, because the mean of its divisors is an integer number (9706368).

Almost surely, 2^191981388 is an apocalyptic number.

It is an amenable number.

191981388 is an abundant number, since it is smaller than the sum of its proper divisors (273924276).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

191981388 is a wasteful number, since it uses less digits than its factorization.

191981388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3942 (or 3940 counting only the distinct ones).

The product of its digits is 124416, while the sum is 48.

The square root of 191981388 is about 13855.7348415737. The cubic root of 191981388 is about 576.8811864449.

The spelling of 191981388 in words is "one hundred ninety-one million, nine hundred eighty-one thousand, three hundred eighty-eight".