18421439 has 2 divisors, whose sum is σ = 18421440. Its totient is φ = 18421438.

The previous prime is 18421433. The next prime is 18421483. The reversal of 18421439 is 93412481.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18421439 - 2²⁰ = 17372863 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18421433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9210719 + 9210720.

It is an arithmetic number, because the mean of its divisors is an integer number (9210720).

Almost surely, 2^18421439 is an apocalyptic number.

18421439 is a deficient number, since it is larger than the sum of its proper divisors (1).

18421439 is an equidigital number, since it uses as much as digits as its factorization.

18421439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 32.

The square root of 18421439 is about 4292.0203867177. The cubic root of 18421439 is about 264.1037193850.

The spelling of 18421439 in words is "eighteen million, four hundred twenty-one thousand, four hundred thirty-nine".