18509873 has 2 divisors, whose sum is σ = 18509874. Its totient is φ = 18509872.

The previous prime is 18509849. The next prime is 18509891. The reversal of 18509873 is 37890581.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16459249 + 2050624 = 4057^2 + 1432^2 .

It is a cyclic number.

It is not a de Polignac number, because 18509873 - 2⁶ = 18509809 is a prime.

It is a super-2 number, since 2×18509873² = 685230796952258, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18509873.

It is not a weakly prime, because it can be changed into another prime (18509473) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9254936 + 9254937.

It is an arithmetic number, because the mean of its divisors is an integer number (9254937).

Almost surely, 2^18509873 is an apocalyptic number.

It is an amenable number.

18509873 is a deficient number, since it is larger than the sum of its proper divisors (1).

18509873 is an equidigital number, since it uses as much as digits as its factorization.

18509873 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 18509873 is about 4302.3101933729. The cubic root of 18509873 is about 264.5256638703.

The spelling of 18509873 in words is "eighteen million, five hundred nine thousand, eight hundred seventy-three".