1320320021 has 4 divisors (see below), whose sum is σ = 1320578700. Its totient is φ = 1320061344.

The previous prime is 1320320017. The next prime is 1320320063. The reversal of 1320320021 is 1200230231.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1200230231 = 173 ⋅6937747.

It can be written as a sum of positive squares in 2 ways, for example, as 912885796 + 407434225 = 30214^2 + 20185^2 .

It is a cyclic number.

It is not a de Polignac number, because 1320320021 - 2² = 1320320017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1320319978 and 1320320005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1320220021) 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, 121526 + ... + 131943.

It is an arithmetic number, because the mean of its divisors is an integer number (330144675).

Almost surely, 2^1320320021 is an apocalyptic number.

It is an amenable number.

1320320021 is a deficient number, since it is larger than the sum of its proper divisors (258679).

1320320021 is an equidigital number, since it uses as much as digits as its factorization.

1320320021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258678.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 1320320021 is about 36336.2081263304. The cubic root of 1320320021 is about 1097.0499524789.

Adding to 1320320021 its reverse (1200230231), we get a palindrome (2520550252).

The spelling of 1320320021 in words is "one billion, three hundred twenty million, three hundred twenty thousand, twenty-one".