18924421 has 2 divisors, whose sum is σ = 18924422. Its totient is φ = 18924420.

The previous prime is 18924407. The next prime is 18924431. The reversal of 18924421 is 12442981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13771521 + 5152900 = 3711^2 + 2270^2 .

It is a cyclic number.

It is not a de Polignac number, because 18924421 - 2¹⁷ = 18793349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18924431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9462210 + 9462211.

It is an arithmetic number, because the mean of its divisors is an integer number (9462211).

Almost surely, 2^18924421 is an apocalyptic number.

It is an amenable number.

18924421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18924421 is an equidigital number, since it uses as much as digits as its factorization.

18924421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4608, while the sum is 31.

The square root of 18924421 is about 4350.2207989940. The cubic root of 18924421 is about 266.4858786769.

The spelling of 18924421 in words is "eighteen million, nine hundred twenty-four thousand, four hundred twenty-one".