18851 has 4 divisors (see below), whose sum is σ = 21552. Its totient is φ = 16152.

The previous prime is 18839. The next prime is 18859. The reversal of 18851 is 15881.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18851 - 2⁶ = 18787 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12 and base 15.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (18859) 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 in 3 ways as a sum of consecutive naturals, for example, 1340 + ... + 1353.

It is an arithmetic number, because the mean of its divisors is an integer number (5388).

2¹⁸⁸⁵¹ is an apocalyptic number.

18851 is a deficient number, since it is larger than the sum of its proper divisors (2701).

18851 is an equidigital number, since it uses as much as digits as its factorization.

18851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2700.

The product of its digits is 320, while the sum is 23.

The square root of 18851 is about 137.2989439144. The cubic root of 18851 is about 26.6140803966.

The spelling of 18851 in words is "eighteen thousand, eight hundred fifty-one".