18001909 has 2 divisors, whose sum is σ = 18001910. Its totient is φ = 18001908.

The previous prime is 18001901. The next prime is 18001931. The reversal of 18001909 is 90910081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15760900 + 2241009 = 3970^2 + 1497^2 .

It is an emirp because it is prime and its reverse (90910081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18001909 - 2³ = 18001901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18001901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9000954 + 9000955.

It is an arithmetic number, because the mean of its divisors is an integer number (9000955).

Almost surely, 2^18001909 is an apocalyptic number.

It is an amenable number.

18001909 is a deficient number, since it is larger than the sum of its proper divisors (1).

18001909 is an equidigital number, since it uses as much as digits as its factorization.

18001909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 18001909 is about 4242.8656589621. The cubic root of 18001909 is about 262.0834038995.

The spelling of 18001909 in words is "eighteen million, one thousand, nine hundred nine".