18554991 has 16 divisors (see below), whose sum is σ = 30449664. Its totient is φ = 9787104.

The previous prime is 18554947. The next prime is 18554999. The reversal of 18554991 is 19945581.

It is not a de Polignac number, because 18554991 - 2¹⁰ = 18553967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18554999) 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, 33711 + ... + 34256.

It is an arithmetic number, because the mean of its divisors is an integer number (1903104).

Almost surely, 2^18554991 is an apocalyptic number.

18554991 is a deficient number, since it is larger than the sum of its proper divisors (11894673).

18554991 is a wasteful number, since it uses less digits than its factorization.

18554991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67990.

The product of its digits is 64800, while the sum is 42.

The square root of 18554991 is about 4307.5504640108. The cubic root of 18554991 is about 264.7404174578.

The spelling of 18554991 in words is "eighteen million, five hundred fifty-four thousand, nine hundred ninety-one".