1261277865 has 16 divisors (see below), whose sum is σ = 2242272000. Its totient is φ = 672681456.

The previous prime is 1261277827. The next prime is 1261277909. The reversal of 1261277865 is 5687721621.

It is a de Polignac number, because none of the positive numbers 2^k-1261277865 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 1261277865.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4671265 + ... + 4671534.

It is an arithmetic number, because the mean of its divisors is an integer number (140142000).

Almost surely, 2^1261277865 is an apocalyptic number.

1261277865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261277865 is a deficient number, since it is larger than the sum of its proper divisors (980994135).

1261277865 is an equidigital number, since it uses as much as digits as its factorization.

1261277865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9342813 (or 9342807 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 1261277865 is about 35514.4740211649. The cubic root of 1261277865 is about 1080.4473069958.

The spelling of 1261277865 in words is "one billion, two hundred sixty-one million, two hundred seventy-seven thousand, eight hundred sixty-five".