11855661 has 4 divisors (see below), whose sum is σ = 15807552. Its totient is φ = 7903772.

The previous prime is 11855653. The next prime is 11855687. The reversal of 11855661 is 16655811.

11855661 is nontrivially palindromic in base 2.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16655811 = 3 ⋅5551937.

It is a cyclic number.

It is not a de Polignac number, because 11855661 - 2³ = 11855653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11857661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1975941 + ... + 1975946.

It is an arithmetic number, because the mean of its divisors is an integer number (3951888).

Almost surely, 2^11855661 is an apocalyptic number.

It is an amenable number.

11855661 is a deficient number, since it is larger than the sum of its proper divisors (3951891).

11855661 is an equidigital number, since it uses as much as digits as its factorization.

11855661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3951890.

The product of its digits is 7200, while the sum is 33.

The square root of 11855661 is about 3443.2050476264. The cubic root of 11855661 is about 228.0212160928.

The spelling of 11855661 in words is "eleven million, eight hundred fifty-five thousand, six hundred sixty-one".