18918239 has 4 divisors (see below), whose sum is σ = 18988320. Its totient is φ = 18848160.

The previous prime is 18918233. The next prime is 18918253. The reversal of 18918239 is 93281981.

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 18918239 - 2¹² = 18914143 is a prime.

It is a super-2 number, since 2×18918239² = 715799533722242, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18918196 and 18918205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18918233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34634 + ... + 35175.

It is an arithmetic number, because the mean of its divisors is an integer number (4747080).

Almost surely, 2^18918239 is an apocalyptic number.

18918239 is a deficient number, since it is larger than the sum of its proper divisors (70081).

18918239 is an equidigital number, since it uses as much as digits as its factorization.

18918239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70080.

The product of its digits is 31104, while the sum is 41.

The square root of 18918239 is about 4349.5102023101. The cubic root of 18918239 is about 266.4568580599.

The spelling of 18918239 in words is "eighteen million, nine hundred eighteen thousand, two hundred thirty-nine".