1231312331 has 4 divisors (see below), whose sum is σ = 1231398000. Its totient is φ = 1231226664.

The previous prime is 1231312319. The next prime is 1231312333. The reversal of 1231312331 is 1332131321.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1332131321 = 127 ⋅10489223.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1231312331 is a prime.

It is a super-2 number, since 2×1231312331² = 3032260112945307122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1231312333) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15431 + ... + 51968.

It is an arithmetic number, because the mean of its divisors is an integer number (307849500).

Almost surely, 2^1231312331 is an apocalyptic number.

1231312331 is a deficient number, since it is larger than the sum of its proper divisors (85669).

1231312331 is an equidigital number, since it uses as much as digits as its factorization.

1231312331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85668.

The product of its digits is 324, while the sum is 20.

The square root of 1231312331 is about 35090.0602877795. The cubic root of 1231312331 is about 1071.8221872576.

Adding to 1231312331 its reverse (1332131321), we get a palindrome (2563443652).

The spelling of 1231312331 in words is "one billion, two hundred thirty-one million, three hundred twelve thousand, three hundred thirty-one".