18879221 has 4 divisors (see below), whose sum is σ = 18939852. Its totient is φ = 18818592.

The previous prime is 18879209. The next prime is 18879239. The reversal of 18879221 is 12297881.

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

It can be written as a sum of positive squares in 2 ways, for example, as 130321 + 18748900 = 361^2 + 4330^2 .

It is a cyclic number.

It is not a de Polignac number, because 18879221 - 2¹⁸ = 18617077 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 (18879271) 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, 29846 + ... + 30471.

It is an arithmetic number, because the mean of its divisors is an integer number (4734963).

Almost surely, 2^18879221 is an apocalyptic number.

It is an amenable number.

18879221 is a deficient number, since it is larger than the sum of its proper divisors (60631).

18879221 is an equidigital number, since it uses as much as digits as its factorization.

18879221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60630.

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

The square root of 18879221 is about 4345.0225546020. The cubic root of 18879221 is about 266.2735469634.

The spelling of 18879221 in words is "eighteen million, eight hundred seventy-nine thousand, two hundred twenty-one".