1320265565 has 4 divisors (see below), whose sum is σ = 1584318684. Its totient is φ = 1056212448.

The previous prime is 1320265501. The next prime is 1320265567. The reversal of 1320265565 is 5655620231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5655620231 = 17 ⋅332683543.

It can be written as a sum of positive squares in 2 ways, for example, as 225780676 + 1094484889 = 15026^2 + 33083^2 .

It is a cyclic number.

It is not a de Polignac number, because 1320265565 - 2⁶ = 1320265501 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 (1320265567) 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, 132026552 + ... + 132026561.

It is an arithmetic number, because the mean of its divisors is an integer number (396079671).

Almost surely, 2^1320265565 is an apocalyptic number.

It is an amenable number.

1320265565 is a deficient number, since it is larger than the sum of its proper divisors (264053119).

1320265565 is an equidigital number, since it uses as much as digits as its factorization.

1320265565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264053118.

The product of its (nonzero) digits is 54000, while the sum is 35.

The square root of 1320265565 is about 36335.4587833978. The cubic root of 1320265565 is about 1097.0348698291.

Adding to 1320265565 its reverse (5655620231), we get a palindrome (6975885796).

The spelling of 1320265565 in words is "one billion, three hundred twenty million, two hundred sixty-five thousand, five hundred sixty-five".