18221879 has 4 divisors (see below), whose sum is σ = 19623576. Its totient is φ = 16820184.

The previous prime is 18221869. The next prime is 18221887. The reversal of 18221879 is 97812281.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18221879 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 (18221869) 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, 700829 + ... + 700854.

It is an arithmetic number, because the mean of its divisors is an integer number (4905894).

Almost surely, 2^18221879 is an apocalyptic number.

18221879 is a deficient number, since it is larger than the sum of its proper divisors (1401697).

18221879 is a wasteful number, since it uses less digits than its factorization.

18221879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1401696.

The product of its digits is 16128, while the sum is 38.

The square root of 18221879 is about 4268.7092897034. The cubic root of 18221879 is about 263.1465735909.

The spelling of 18221879 in words is "eighteen million, two hundred twenty-one thousand, eight hundred seventy-nine".