991749231 has 32 divisors (see below), whose sum is σ = 1630022400. Its totient is φ = 590862240.

The previous prime is 991749191. The next prime is 991749263. The reversal of 991749231 is 132947199.

It is not a de Polignac number, because 991749231 - 2⁷ = 991749103 is a prime.

It is a super-2 number, since 2×991749231² = 1967133074378182722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991744231) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10776 + ... + 45821.

It is an arithmetic number, because the mean of its divisors is an integer number (50938200).

Almost surely, 2^991749231 is an apocalyptic number.

991749231 is a deficient number, since it is larger than the sum of its proper divisors (638273169).

991749231 is a wasteful number, since it uses less digits than its factorization.

991749231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56676 (or 56670 counting only the distinct ones).

The product of its digits is 122472, while the sum is 45.

The square root of 991749231 is about 31492.0502825713. The cubic root of 991749231 is about 997.2421448937.

The spelling of 991749231 in words is "nine hundred ninety-one million, seven hundred forty-nine thousand, two hundred thirty-one".