20618 has 12 divisors (see below), whose sum is σ = 34038. Its totient is φ = 9360.

The previous prime is 20611. The next prime is 20627. The reversal of 20618 is 81602.

It can be written as a sum of positive squares in 3 ways, for example, as 4489 + 16129 = 67^2 + 127^2 .

It is a Smith number, since the sum of its digits (17) coincides with the sum of the digits of its prime factors.

It is a nialpdrome in base 12 and base 13.

It is a zygodrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 20596 and 20605.

It is not an unprimeable number, because it can be changed into a prime (20611) by changing a digit.

20618 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 308 + ... + 368.

2²⁰⁶¹⁸ is an apocalyptic number.

20618 is a deficient number, since it is larger than the sum of its proper divisors (13420).

20618 is a wasteful number, since it uses less digits than its factorization.

20618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89 (or 76 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 20618 is about 143.5896932234. The cubic root of 20618 is about 27.4209298943.

The spelling of 20618 in words is "twenty thousand, six hundred eighteen".