18919879 has 4 divisors (see below), whose sum is σ = 20639880. Its totient is φ = 17199880.

The previous prime is 18919843. The next prime is 18919883. The reversal of 18919879 is 97891981.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18919879 - 2²¹ = 16822727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18919379) 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 3 ways as a sum of consecutive naturals, for example, 859984 + ... + 860005.

It is an arithmetic number, because the mean of its divisors is an integer number (5159970).

Almost surely, 2^18919879 is an apocalyptic number.

18919879 is a deficient number, since it is larger than the sum of its proper divisors (1720001).

18919879 is a wasteful number, since it uses less digits than its factorization.

18919879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1720000.

The product of its digits is 326592, while the sum is 52.

The square root of 18919879 is about 4349.6987251993. The cubic root of 18919879 is about 266.4645574485.

The spelling of 18919879 in words is "eighteen million, nine hundred nineteen thousand, eight hundred seventy-nine".