18664259 has 2 divisors, whose sum is σ = 18664260. Its totient is φ = 18664258.

The previous prime is 18664253. The next prime is 18664273. The reversal of 18664259 is 95246681.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18664259 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (18664253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9332129 + 9332130.

It is an arithmetic number, because the mean of its divisors is an integer number (9332130).

Almost surely, 2^18664259 is an apocalyptic number.

18664259 is a deficient number, since it is larger than the sum of its proper divisors (1).

18664259 is an equidigital number, since it uses as much as digits as its factorization.

18664259 is an evil number, because the sum of its binary digits is even.

The product of its digits is 103680, while the sum is 41.

The square root of 18664259 is about 4320.2151566791. The cubic root of 18664259 is about 265.2590749844.

The spelling of 18664259 in words is "eighteen million, six hundred sixty-four thousand, two hundred fifty-nine".