191968591 has 4 divisors (see below), whose sum is σ = 193349800. Its totient is φ = 190587384.

The previous prime is 191968589. The next prime is 191968627. The reversal of 191968591 is 195869191.

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

It is a cyclic number.

It is not a de Polignac number, because 191968591 - 2¹ = 191968589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191968531) 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, 690396 + ... + 690673.

It is an arithmetic number, because the mean of its divisors is an integer number (48337450).

Almost surely, 2^191968591 is an apocalyptic number.

191968591 is a deficient number, since it is larger than the sum of its proper divisors (1381209).

191968591 is a wasteful number, since it uses less digits than its factorization.

191968591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1381208.

The product of its digits is 174960, while the sum is 49.

The square root of 191968591 is about 13855.2730395326. The cubic root of 191968591 is about 576.8683683402.

The spelling of 191968591 in words is "one hundred ninety-one million, nine hundred sixty-eight thousand, five hundred ninety-one".