18791 has 8 divisors (see below), whose sum is σ = 21120. Its totient is φ = 16632.

The previous prime is 18787. The next prime is 18793. The reversal of 18791 is 19781.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18791 - 2² = 18787 is a prime.

It is a Duffinian number.

It is a plaindrome in base 6.

It is a zygodrome in base 6.

It is a self number, because there is not a number n which added to its sum of digits gives 18791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18793) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 416 + ... + 458.

It is an arithmetic number, because the mean of its divisors is an integer number (2640).

2¹⁸⁷⁹¹ is an apocalyptic number.

18791 is a deficient number, since it is larger than the sum of its proper divisors (2329).

18791 is a wasteful number, since it uses less digits than its factorization.

18791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85.

The product of its digits is 504, while the sum is 26.

The square root of 18791 is about 137.0802684561. The cubic root of 18791 is about 26.5858141331.

Multiplying 18791 by its sum of digits (26), we get a triangular number (488566 = T₉₈₈).

Subtracting 18791 from its reverse (19781), we obtain a triangular number (990 = T₄₄).

The spelling of 18791 in words is "eighteen thousand, seven hundred ninety-one".