18920421 has 48 divisors (see below), whose sum is σ = 31449600. Its totient is φ = 10872576.

The previous prime is 18920413. The next prime is 18920449. The reversal of 18920421 is 12402981.

It is not a de Polignac number, because 18920421 - 2³ = 18920413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18920521) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 212545 + ... + 212633.

It is an arithmetic number, because the mean of its divisors is an integer number (655200).

Almost surely, 2^18920421 is an apocalyptic number.

It is an amenable number.

18920421 is a deficient number, since it is larger than the sum of its proper divisors (12529179).

18920421 is a wasteful number, since it uses less digits than its factorization.

18920421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210 (or 207 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 18920421 is about 4349.7610279187. The cubic root of 18920421 is about 266.4671019047.

It can be divided in two parts, 189204 and 21, that added together give a square (189225 = 435²).

The spelling of 18920421 in words is "eighteen million, nine hundred twenty thousand, four hundred twenty-one".