18939439 has 2 divisors, whose sum is σ = 18939440. Its totient is φ = 18939438.

The previous prime is 18939421. The next prime is 18939443. The reversal of 18939439 is 93493981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18939439 - 2²³ = 10550831 is a prime.

It is a Chen prime.

It is a nialpdrome in base 11.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18934439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9469719 + 9469720.

It is an arithmetic number, because the mean of its divisors is an integer number (9469720).

Almost surely, 2^18939439 is an apocalyptic number.

18939439 is a deficient number, since it is larger than the sum of its proper divisors (1).

18939439 is an equidigital number, since it uses as much as digits as its factorization.

18939439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 46.

The square root of 18939439 is about 4351.9465759589. The cubic root of 18939439 is about 266.5563524620.

The spelling of 18939439 in words is "eighteen million, nine hundred thirty-nine thousand, four hundred thirty-nine".