18972591 has 16 divisors (see below), whose sum is σ = 28011648. Its totient is φ = 11325600.

The previous prime is 18972581. The next prime is 18972607. The reversal of 18972591 is 19527981.

It is not a de Polignac number, because 18972591 - 2¹⁰ = 18971567 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18972581) 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, 2080 + ... + 6501.

It is an arithmetic number, because the mean of its divisors is an integer number (1750728).

Almost surely, 2^18972591 is an apocalyptic number.

18972591 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18972591 is a deficient number, since it is larger than the sum of its proper divisors (9039057).

18972591 is a wasteful number, since it uses less digits than its factorization.

18972591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8662.

The product of its digits is 45360, while the sum is 42.

The square root of 18972591 is about 4355.7537809201. The cubic root of 18972591 is about 266.7117904543.

The spelling of 18972591 in words is "eighteen million, nine hundred seventy-two thousand, five hundred ninety-one".