18688909 has 2 divisors, whose sum is σ = 18688910. Its totient is φ = 18688908.

The previous prime is 18688897. The next prime is 18688927. The reversal of 18688909 is 90988681.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10220809 + 8468100 = 3197^2 + 2910^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18688909 is a prime.

It is a super-2 number, since 2×18688909² = 698550639220562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18688979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9344454 + 9344455.

It is an arithmetic number, because the mean of its divisors is an integer number (9344455).

Almost surely, 2^18688909 is an apocalyptic number.

It is an amenable number.

18688909 is a deficient number, since it is larger than the sum of its proper divisors (1).

18688909 is an equidigital number, since it uses as much as digits as its factorization.

18688909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 248832, while the sum is 49.

The square root of 18688909 is about 4323.0670825237. The cubic root of 18688909 is about 265.3758000357.

The spelling of 18688909 in words is "eighteen million, six hundred eighty-eight thousand, nine hundred nine".