18939287 has 2 divisors, whose sum is σ = 18939288. Its totient is φ = 18939286.

The previous prime is 18939259. The next prime is 18939293. The reversal of 18939287 is 78293981.

It is a strong prime.

It is an emirp because it is prime and its reverse (78293981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18939287 - 2⁸ = 18939031 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18939247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9469643 + 9469644.

It is an arithmetic number, because the mean of its divisors is an integer number (9469644).

Almost surely, 2^18939287 is an apocalyptic number.

18939287 is a deficient number, since it is larger than the sum of its proper divisors (1).

18939287 is an equidigital number, since it uses as much as digits as its factorization.

18939287 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 47.

The square root of 18939287 is about 4351.9291124741. The cubic root of 18939287 is about 266.5556393702. Note that the first 3 decimals are identical.

The spelling of 18939287 in words is "eighteen million, nine hundred thirty-nine thousand, two hundred eighty-seven".