18500309 has 2 divisors, whose sum is σ = 18500310. Its totient is φ = 18500308.

The previous prime is 18500291. The next prime is 18500311. The reversal of 18500309 is 90300581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 36100 = 4297^2 + 190^2 .

It is a cyclic number.

It is not a de Polignac number, because 18500309 - 2¹² = 18496213 is a prime.

It is a super-2 number, since 2×18500309² = 684522866190962, which contains 22 as substring.

Together with 18500311, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1181177 and since 18500309 and 1181177 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18500329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9250154 + 9250155.

It is an arithmetic number, because the mean of its divisors is an integer number (9250155).

Almost surely, 2^18500309 is an apocalyptic number.

It is an amenable number.

18500309 is a deficient number, since it is larger than the sum of its proper divisors (1).

18500309 is an equidigital number, since it uses as much as digits as its factorization.

18500309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 18500309 is about 4301.1985538917. The cubic root of 18500309 is about 264.4800961291.

The spelling of 18500309 in words is "eighteen million, five hundred thousand, three hundred nine".