18551961 has 48 divisors (see below), whose sum is σ = 30326400. Its totient is φ = 10872576.

The previous prime is 18551959. The next prime is 18551969. The reversal of 18551961 is 16915581.

18551961 is a `hidden beast` number, since 1 + 85 + 519 + 61 = 666.

It is not a de Polignac number, because 18551961 - 2¹ = 18551959 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18551969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 208405 + ... + 208493.

It is an arithmetic number, because the mean of its divisors is an integer number (631800).

Almost surely, 2^18551961 is an apocalyptic number.

It is an amenable number.

18551961 is a deficient number, since it is larger than the sum of its proper divisors (11774439).

18551961 is a wasteful number, since it uses less digits than its factorization.

18551961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190 (or 187 counting only the distinct ones).

The product of its digits is 10800, while the sum is 36.

The square root of 18551961 is about 4307.1987416417. The cubic root of 18551961 is about 264.7260061128.

The spelling of 18551961 in words is "eighteen million, five hundred fifty-one thousand, nine hundred sixty-one".