1320278021 has 4 divisors (see below), whose sum is σ = 1397941452. Its totient is φ = 1242614592.

The previous prime is 1320278009. The next prime is 1320278051. The reversal of 1320278021 is 1208720231.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1034329921 + 285948100 = 32161^2 + 16910^2 .

It is not a de Polignac number, because 1320278021 - 2²⁶ = 1253169157 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 (1320278051) 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, 38831690 + ... + 38831723.

It is an arithmetic number, because the mean of its divisors is an integer number (349485363).

Almost surely, 2^1320278021 is an apocalyptic number.

It is an amenable number.

1320278021 is a deficient number, since it is larger than the sum of its proper divisors (77663431).

1320278021 is an equidigital number, since it uses as much as digits as its factorization.

1320278021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77663430.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 1320278021 is about 36335.6301858107. The cubic root of 1320278021 is about 1097.0383197975.

Adding to 1320278021 its reverse (1208720231), we get a palindrome (2528998252).

The spelling of 1320278021 in words is "one billion, three hundred twenty million, two hundred seventy-eight thousand, twenty-one".