18637 has 2 divisors, whose sum is σ = 18638. Its totient is φ = 18636.

The previous prime is 18617. The next prime is 18661. The reversal of 18637 is 73681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9801 + 8836 = 99^2 + 94^2 .

It is an emirp because it is prime and its reverse (73681) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18637 is a prime.

It is a plaindrome in base 16.

It is a nialpdrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9318 + 9319.

It is an arithmetic number, because the mean of its divisors is an integer number (9319).

2¹⁸⁶³⁷ is an apocalyptic number.

It is an amenable number.

18637 is a deficient number, since it is larger than the sum of its proper divisors (1).

18637 is an equidigital number, since it uses as much as digits as its factorization.

18637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 25.

The square root of 18637 is about 136.5173981586. The cubic root of 18637 is about 26.5129875818.

It can be divided in two parts, 1863 and 7, that multiplied together give a triangular number (13041 = T₁₆₁).

The spelling of 18637 in words is "eighteen thousand, six hundred thirty-seven".