11555865 has 24 divisors (see below), whose sum is σ = 20774208. Its totient is φ = 6162480.

The previous prime is 11555783. The next prime is 11555909. The reversal of 11555865 is 56855511.

It is not a de Polignac number, because 11555865 - 2⁷ = 11555737 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3541 + ... + 5970.

It is an arithmetic number, because the mean of its divisors is an integer number (865592).

Almost surely, 2^11555865 is an apocalyptic number.

11555865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

11555865 is a deficient number, since it is larger than the sum of its proper divisors (9218343).

11555865 is an frugal number, since it uses more digits than its factorization.

11555865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9531 (or 9519 counting only the distinct ones).

The product of its digits is 30000, while the sum is 36.

The square root of 11555865 is about 3399.3918573768. The cubic root of 11555865 is about 226.0827809103.

The spelling of 11555865 in words is "eleven million, five hundred fifty-five thousand, eight hundred sixty-five".