1231320321 has 36 divisors (see below), whose sum is σ = 2234255296. Its totient is φ = 639642960.

The previous prime is 1231320317. The next prime is 1231320427. The reversal of 1231320321 is 1230231321.

1231320321 is a `hidden beast` number, since 1 + 23 + 1 + 320 + 321 = 666.

It is not a de Polignac number, because 1231320321 - 2² = 1231320317 is a prime.

It is a super-2 number, since 2×1231320321² = 3032299465815086082, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1231320294 and 1231320303.

It is not an unprimeable number, because it can be changed into a prime (1231320721) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 73141 + ... + 88386.

Almost surely, 2^1231320321 is an apocalyptic number.

1231320321 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1231320321 is a deficient number, since it is larger than the sum of its proper divisors (1002934975).

1231320321 is a wasteful number, since it uses less digits than its factorization.

1231320321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161562 (or 161548 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 1231320321 is about 35090.1741374989. The cubic root of 1231320321 is about 1071.8245056081.

Adding to 1231320321 its reverse (1230231321), we get a palindrome (2461551642).

The spelling of 1231320321 in words is "one billion, two hundred thirty-one million, three hundred twenty thousand, three hundred twenty-one".