1331665565 has 4 divisors (see below), whose sum is σ = 1597998684. Its totient is φ = 1065332448.

The previous prime is 1331665541. The next prime is 1331665583. The reversal of 1331665565 is 5655661331.

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: 5655661331 = 30103 ⋅187877.

It can be written as a sum of positive squares in 2 ways, for example, as 280998169 + 1050667396 = 16763^2 + 32414^2 .

It is a cyclic number.

It is not a de Polignac number, because 1331665565 - 2²² = 1327471261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133166552 + ... + 133166561.

It is an arithmetic number, because the mean of its divisors is an integer number (399499671).

Almost surely, 2^1331665565 is an apocalyptic number.

It is an amenable number.

1331665565 is a deficient number, since it is larger than the sum of its proper divisors (266333119).

1331665565 is an equidigital number, since it uses as much as digits as its factorization.

1331665565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266333118.

The product of its digits is 243000, while the sum is 41.

The square root of 1331665565 is about 36491.9931628844. The cubic root of 1331665565 is about 1100.1833206866.

The spelling of 1331665565 in words is "one billion, three hundred thirty-one million, six hundred sixty-five thousand, five hundred sixty-five".