991992131 has 16 divisors (see below), whose sum is σ = 1091563200. Its totient is φ = 895961088.

The previous prime is 991992059. The next prime is 991992161. The reversal of 991992131 is 131299199.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991992131 is a prime.

It is a super-2 number, since 2×991992131² = 1968096775931842322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (991992161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107810 + ... + 116648.

It is an arithmetic number, because the mean of its divisors is an integer number (68222700).

Almost surely, 2^991992131 is an apocalyptic number.

991992131 is a deficient number, since it is larger than the sum of its proper divisors (99571069).

991992131 is a wasteful number, since it uses less digits than its factorization.

991992131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9038.

The product of its digits is 39366, while the sum is 44.

The square root of 991992131 is about 31495.9065752996. The cubic root of 991992131 is about 997.3235533575.

The spelling of 991992131 in words is "nine hundred ninety-one million, nine hundred ninety-two thousand, one hundred thirty-one".