1321331021 has 4 divisors (see below), whose sum is σ = 1322665344. Its totient is φ = 1319996700.

The previous prime is 1321330991. The next prime is 1321331057. The reversal of 1321331021 is 1201331231.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1321331021 - 2¹⁸ = 1321068877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321331521) 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, 665675 + ... + 667656.

It is an arithmetic number, because the mean of its divisors is an integer number (330666336).

Almost surely, 2^1321331021 is an apocalyptic number.

It is an amenable number.

1321331021 is a deficient number, since it is larger than the sum of its proper divisors (1334323).

1321331021 is an equidigital number, since it uses as much as digits as its factorization.

1321331021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1334322.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 1321331021 is about 36350.1172075139. The cubic root of 1321331021 is about 1097.3298933297.

Adding to 1321331021 its reverse (1201331231), we get a palindrome (2522662252).

The spelling of 1321331021 in words is "one billion, three hundred twenty-one million, three hundred thirty-one thousand, twenty-one".