11991805 has 16 divisors (see below), whose sum is σ = 16657920. Its totient is φ = 8116992.

The previous prime is 11991781. The next prime is 11991839. The reversal of 11991805 is 50819911.

It is a cyclic number.

It is not a de Polignac number, because 11991805 - 2⁵ = 11991773 is a prime.

It is a congruent number.

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, 597 + ... + 4933.

It is an arithmetic number, because the mean of its divisors is an integer number (1041120).

Almost surely, 2^11991805 is an apocalyptic number.

It is an amenable number.

11991805 is a deficient number, since it is larger than the sum of its proper divisors (4666115).

11991805 is an equidigital number, since it uses as much as digits as its factorization.

11991805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4428.

The product of its (nonzero) digits is 3240, while the sum is 34.

The square root of 11991805 is about 3462.9185667584. The cubic root of 11991805 is about 228.8907203468.

The spelling of 11991805 in words is "eleven million, nine hundred ninety-one thousand, eight hundred five".