1321391231 has 4 divisors (see below), whose sum is σ = 1327062672. Its totient is φ = 1315719792.

The previous prime is 1321391189. The next prime is 1321391261. The reversal of 1321391231 is 1321931231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1321931231 = 73 ⋅18108647.

It is a cyclic number.

It is not a de Polignac number, because 1321391231 - 2³⁰ = 247649407 is a prime.

It is a super-2 number, since 2×1321391231² = 3492149570727390722, which contains 22 as substring.

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 1321391231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321391261) 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, 2835371 + ... + 2835836.

It is an arithmetic number, because the mean of its divisors is an integer number (331765668).

Almost surely, 2^1321391231 is an apocalyptic number.

1321391231 is a deficient number, since it is larger than the sum of its proper divisors (5671441).

1321391231 is an equidigital number, since it uses as much as digits as its factorization.

1321391231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5671440.

The product of its digits is 972, while the sum is 26.

The square root of 1321391231 is about 36350.9453934832. The cubic root of 1321391231 is about 1097.3465606720.

The spelling of 1321391231 in words is "one billion, three hundred twenty-one million, three hundred ninety-one thousand, two hundred thirty-one".