1265204665 has 4 divisors (see below), whose sum is σ = 1518245604. Its totient is φ = 1012163728.

The previous prime is 1265204653. The next prime is 1265204669. The reversal of 1265204665 is 5664025621.

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 852464809 + 412739856 = 29197^2 + 20316^2 .

It is a cyclic number.

It is not a de Polignac number, because 1265204665 - 2²¹ = 1263107513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1265204669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126520462 + ... + 126520471.

It is an arithmetic number, because the mean of its divisors is an integer number (379561401).

Almost surely, 2^1265204665 is an apocalyptic number.

It is an amenable number.

1265204665 is a deficient number, since it is larger than the sum of its proper divisors (253040939).

1265204665 is an equidigital number, since it uses as much as digits as its factorization.

1265204665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253040938.

The product of its (nonzero) digits is 86400, while the sum is 37.

The square root of 1265204665 is about 35569.7155597286. The cubic root of 1265204665 is about 1081.5674157358.

The spelling of 1265204665 in words is "one billion, two hundred sixty-five million, two hundred four thousand, six hundred sixty-five".