15855561 has 16 divisors (see below), whose sum is σ = 24064320. Its totient is φ = 10311840.

The previous prime is 15855551. The next prime is 15855563. The reversal of 15855561 is 16555851.

15855561 is a `hidden beast` number, since 15 + 85 + 5 + 561 = 666.

It is not a de Polignac number, because 15855561 - 2²² = 11661257 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15855563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6055 + ... + 8268.

It is an arithmetic number, because the mean of its divisors is an integer number (1504020).

Almost surely, 2^15855561 is an apocalyptic number.

It is an amenable number.

15855561 is a deficient number, since it is larger than the sum of its proper divisors (8208759).

15855561 is a wasteful number, since it uses less digits than its factorization.

15855561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14373 (or 14367 counting only the distinct ones).

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

The square root of 15855561 is about 3981.9041927199. The cubic root of 15855561 is about 251.2236595242.

The spelling of 15855561 in words is "fifteen million, eight hundred fifty-five thousand, five hundred sixty-one".