1231362991 has 4 divisors (see below), whose sum is σ = 1232359672. Its totient is φ = 1230366312.

The previous prime is 1231362959. The next prime is 1231363027. The reversal of 1231362991 is 1992631321.

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 1231362991 - 2⁵ = 1231362959 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1231362991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231362901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 496485 + ... + 498958.

It is an arithmetic number, because the mean of its divisors is an integer number (308089918).

Almost surely, 2^1231362991 is an apocalyptic number.

1231362991 is a deficient number, since it is larger than the sum of its proper divisors (996681).

1231362991 is an equidigital number, since it uses as much as digits as its factorization.

1231362991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 996680.

The product of its digits is 17496, while the sum is 37.

The square root of 1231362991 is about 35090.7821371938. The cubic root of 1231362991 is about 1071.8368864166.

The spelling of 1231362991 in words is "one billion, two hundred thirty-one million, three hundred sixty-two thousand, nine hundred ninety-one".