18550331 has 2 divisors, whose sum is σ = 18550332. Its totient is φ = 18550330.

The previous prime is 18550321. The next prime is 18550333. The reversal of 18550331 is 13305581.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18550331 is a prime.

It is a super-2 number, since 2×18550331² = 688229560419122, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 18550333, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18550331.

It is not a weakly prime, because it can be changed into another prime (18550333) 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, 9275165 + 9275166.

It is an arithmetic number, because the mean of its divisors is an integer number (9275166).

Almost surely, 2^18550331 is an apocalyptic number.

18550331 is a deficient number, since it is larger than the sum of its proper divisors (1).

18550331 is an equidigital number, since it uses as much as digits as its factorization.

18550331 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 18550331 is about 4307.0095193765. The cubic root of 18550331 is about 264.7182528259.

It can be divided in two parts, 18550 and 331, that added together give a palindrome (18881).

The spelling of 18550331 in words is "eighteen million, five hundred fifty thousand, three hundred thirty-one".