18931121 has 4 divisors (see below), whose sum is σ = 20652144. Its totient is φ = 17210100.

The previous prime is 18931117. The next prime is 18931127. The reversal of 18931121 is 12113981.

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.

It is a cyclic number.

It is not a de Polignac number, because 18931121 - 2² = 18931117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18931127) 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, 860495 + ... + 860516.

It is an arithmetic number, because the mean of its divisors is an integer number (5163036).

Almost surely, 2^18931121 is an apocalyptic number.

18931121 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18931121 is a deficient number, since it is larger than the sum of its proper divisors (1721023).

18931121 is a wasteful number, since it uses less digits than its factorization.

18931121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1721022.

The product of its digits is 432, while the sum is 26.

The square root of 18931121 is about 4350.9908067014. The cubic root of 18931121 is about 266.5173238436.

It can be divided in two parts, 18 and 931121, that added together give a palindrome (931139).

The spelling of 18931121 in words is "eighteen million, nine hundred thirty-one thousand, one hundred twenty-one".