18761 has 4 divisors (see below), whose sum is σ = 19092. Its totient is φ = 18432.

The previous prime is 18757. The next prime is 18773. The reversal of 18761 is 16781.

18761 is nontrivially palindromic in base 2.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16781 = 97 ⋅173.

It can be written as a sum of positive squares in 2 ways, for example, as 15625 + 3136 = 125^2 + 56^2 .

It is a cyclic number.

It is not a de Polignac number, because 18761 - 2² = 18757 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

18761 is an undulating number in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56 + ... + 201.

It is an arithmetic number, because the mean of its divisors is an integer number (4773).

2¹⁸⁷⁶¹ is an apocalyptic number.

It is an amenable number.

18761 is a deficient number, since it is larger than the sum of its proper divisors (331).

18761 is an equidigital number, since it uses as much as digits as its factorization.

18761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330.

The product of its digits is 336, while the sum is 23.

The square root of 18761 is about 136.9707998078. The cubic root of 18761 is about 26.5716584336.

The spelling of 18761 in words is "eighteen thousand, seven hundred sixty-one".