18644239 has 2 divisors, whose sum is σ = 18644240. Its totient is φ = 18644238.

The previous prime is 18644233. The next prime is 18644251. The reversal of 18644239 is 93244681.

It is a weak prime.

It is an emirp because it is prime and its reverse (93244681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18644239 - 2¹³ = 18636047 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18644198 and 18644207.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18644233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9322119 + 9322120.

It is an arithmetic number, because the mean of its divisors is an integer number (9322120).

Almost surely, 2^18644239 is an apocalyptic number.

18644239 is a deficient number, since it is larger than the sum of its proper divisors (1).

18644239 is an equidigital number, since it uses as much as digits as its factorization.

18644239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 37.

The square root of 18644239 is about 4317.8975207849. The cubic root of 18644239 is about 265.1641987014.

The spelling of 18644239 in words is "eighteen million, six hundred forty-four thousand, two hundred thirty-nine".