191291223921 has 24 divisors (see below), whose sum is σ = 296788541184. Its totient is φ = 109275395040.

The previous prime is 191291223911. The next prime is 191291223943. The reversal of 191291223921 is 129322192191.

It is not a de Polignac number, because 191291223921 - 2¹¹ = 191291221873 is a prime.

It is a super-2 number, since 2×191291223921² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (191291223911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 278176 + ... + 678206.

It is an arithmetic number, because the mean of its divisors is an integer number (12366189216).

Almost surely, 2^191291223921 is an apocalyptic number.

It is an amenable number.

191291223921 is a deficient number, since it is larger than the sum of its proper divisors (105497317263).

191291223921 is a wasteful number, since it uses less digits than its factorization.

191291223921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403301 (or 403294 counting only the distinct ones).

The product of its digits is 34992, while the sum is 42.

The spelling of 191291223921 in words is "one hundred ninety-one billion, two hundred ninety-one million, two hundred twenty-three thousand, nine hundred twenty-one".