991112831 has 2 divisors, whose sum is σ = 991112832. Its totient is φ = 991112830.

The previous prime is 991112813. The next prime is 991112839. The reversal of 991112831 is 138211199.

Together with previous prime (991112813) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991112831 is a prime.

It is a super-2 number, since 2×991112831² = 1964609287545669122, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 991112791 and 991112800.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991112839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495556415 + 495556416.

It is an arithmetic number, because the mean of its divisors is an integer number (495556416).

Almost surely, 2^991112831 is an apocalyptic number.

991112831 is a deficient number, since it is larger than the sum of its proper divisors (1).

991112831 is an equidigital number, since it uses as much as digits as its factorization.

991112831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 35.

The square root of 991112831 is about 31481.9445238060. The cubic root of 991112831 is about 997.0287909937.

The spelling of 991112831 in words is "nine hundred ninety-one million, one hundred twelve thousand, eight hundred thirty-one".