18621 has 6 divisors (see below), whose sum is σ = 26910. Its totient is φ = 12408.

The previous prime is 18617. The next prime is 18637. The reversal of 18621 is 12681.

18621 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 12996 + 5625 = 114^2 + 75^2 .

It is not a de Polignac number, because 18621 - 2² = 18617 is a prime.

It is a Curzon number.

18621 is a lucky number.

It is a plaindrome in base 16.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 18594 and 18603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1026 + ... + 1043.

It is an arithmetic number, because the mean of its divisors is an integer number (4485).

2¹⁸⁶²¹ is an apocalyptic number.

It is an amenable number.

18621 is a deficient number, since it is larger than the sum of its proper divisors (8289).

18621 is a wasteful number, since it uses less digits than its factorization.

18621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2075 (or 2072 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 18621 is about 136.4587849865. The cubic root of 18621 is about 26.5053982120.

The spelling of 18621 in words is "eighteen thousand, six hundred twenty-one".