18869991 has 16 divisors (see below), whose sum is σ = 29424384. Its totient is φ = 10531584.

The previous prime is 18869957. The next prime is 18870011. The reversal of 18869991 is 19996881.

It is a happy number.

It is not a de Polignac number, because 18869991 - 2⁶ = 18869927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18869791) 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, 9546 + ... + 11351.

It is an arithmetic number, because the mean of its divisors is an integer number (1839024).

Almost surely, 2^18869991 is an apocalyptic number.

18869991 is a deficient number, since it is larger than the sum of its proper divisors (10554393).

18869991 is a wasteful number, since it uses less digits than its factorization.

18869991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20950.

The product of its digits is 279936, while the sum is 51.

The square root of 18869991 is about 4343.9602898737. The cubic root of 18869991 is about 266.2301464180.

The spelling of 18869991 in words is "eighteen million, eight hundred sixty-nine thousand, nine hundred ninety-one".