191916881 has 4 divisors (see below), whose sum is σ = 206679732. Its totient is φ = 177154032.

The previous prime is 191916847. The next prime is 191916887. The reversal of 191916881 is 188619191.

191916881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 43296400 + 148620481 = 6580^2 + 12191^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191916881 is a prime.

It is a super-2 number, since 2×191916881² = 73664178425536322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191916887) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7381406 + ... + 7381431.

It is an arithmetic number, because the mean of its divisors is an integer number (51669933).

Almost surely, 2^191916881 is an apocalyptic number.

It is an amenable number.

191916881 is a deficient number, since it is larger than the sum of its proper divisors (14762851).

191916881 is a wasteful number, since it uses less digits than its factorization.

191916881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14762850.

The product of its digits is 31104, while the sum is 44.

The square root of 191916881 is about 13853.4068373090. The cubic root of 191916881 is about 576.8165672583.

The spelling of 191916881 in words is "one hundred ninety-one million, nine hundred sixteen thousand, eight hundred eighty-one".