18722421 has 12 divisors (see below), whose sum is σ = 28045472. Its totient is φ = 12481452.

The previous prime is 18722377. The next prime is 18722449. The reversal of 18722421 is 12422781.

It is not a de Polignac number, because 18722421 - 2¹⁵ = 18689653 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18722461) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38281 + ... + 38766.

Almost surely, 2^18722421 is an apocalyptic number.

It is an amenable number.

18722421 is a deficient number, since it is larger than the sum of its proper divisors (9323051).

18722421 is an frugal number, since it uses more digits than its factorization.

18722421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77062 (or 77050 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 18722421 is about 4326.9412984232. The cubic root of 18722421 is about 265.5343247779.

The spelling of 18722421 in words is "eighteen million, seven hundred twenty-two thousand, four hundred twenty-one".