1261631265 has 8 divisors (see below), whose sum is σ = 2018610048. Its totient is φ = 672870000.

The previous prime is 1261631243. The next prime is 1261631317. The reversal of 1261631265 is 5621361621.

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

It is not a de Polignac number, because 1261631265 - 2⁸ = 1261631009 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42054361 + ... + 42054390.

It is an arithmetic number, because the mean of its divisors is an integer number (252326256).

Almost surely, 2^1261631265 is an apocalyptic number.

1261631265 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261631265 is a deficient number, since it is larger than the sum of its proper divisors (756978783).

1261631265 is an equidigital number, since it uses as much as digits as its factorization.

1261631265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84108759.

The product of its digits is 12960, while the sum is 33.

The square root of 1261631265 is about 35519.4491089037. The cubic root of 1261631265 is about 1080.5482084790.

Adding to 1261631265 its reverse (5621361621), we get a palindrome (6882992886).

The spelling of 1261631265 in words is "one billion, two hundred sixty-one million, six hundred thirty-one thousand, two hundred sixty-five".