1265516665 has 16 divisors (see below), whose sum is σ = 1764984960. Its totient is φ = 853073280.

The previous prime is 1265516663. The next prime is 1265516671. The reversal of 1265516665 is 5666155621.

It is not a de Polignac number, because 1265516665 - 2¹ = 1265516663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1265516663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 304356 + ... + 308485.

It is an arithmetic number, because the mean of its divisors is an integer number (110311560).

Almost surely, 2^1265516665 is an apocalyptic number.

It is an amenable number.

1265516665 is a deficient number, since it is larger than the sum of its proper divisors (499468295).

1265516665 is an equidigital number, since it uses as much as digits as its factorization.

1265516665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 612912.

The product of its digits is 324000, while the sum is 43.

The square root of 1265516665 is about 35574.1010427530. The cubic root of 1265516665 is about 1081.6563134213.

The spelling of 1265516665 in words is "one billion, two hundred sixty-five million, five hundred sixteen thousand, six hundred sixty-five".