1265635661 has 8 divisors (see below), whose sum is σ = 1309677600. Its totient is φ = 1221620400.

The previous prime is 1265635639. The next prime is 1265635687. The reversal of 1265635661 is 1665365621.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1265635661 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 (1265635621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165950 + ... + 173408.

It is an arithmetic number, because the mean of its divisors is an integer number (163709700).

Almost surely, 2^1265635661 is an apocalyptic number.

It is an amenable number.

1265635661 is a deficient number, since it is larger than the sum of its proper divisors (44041939).

1265635661 is an equidigital number, since it uses as much as digits as its factorization.

1265635661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13339.

The product of its digits is 194400, while the sum is 41.

The square root of 1265635661 is about 35575.7735123216. The cubic root of 1265635661 is about 1081.6902149216.

The spelling of 1265635661 in words is "one billion, two hundred sixty-five million, six hundred thirty-five thousand, six hundred sixty-one".