20555 has 4 divisors (see below), whose sum is σ = 24672. Its totient is φ = 16440.

The previous prime is 20551. The next prime is 20563. The reversal of 20555 is 55502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55502 = 2 ⋅27751.

It is not a de Polignac number, because 20555 - 2² = 20551 is a prime.

It is a Duffinian number.

20555 is a modest number, since divided by 555 gives 20 as remainder.

It is not an unprimeable number, because it can be changed into a prime (20551) 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, 2051 + ... + 2060.

It is an arithmetic number, because the mean of its divisors is an integer number (6168).

2²⁰⁵⁵⁵ is an apocalyptic number.

20555 is a deficient number, since it is larger than the sum of its proper divisors (4117).

20555 is an equidigital number, since it uses as much as digits as its factorization.

20555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4116.

The product of its (nonzero) digits is 250, while the sum is 17.

The square root of 20555 is about 143.3701503103. The cubic root of 20555 is about 27.3929724283.

It can be divided in two parts, 20 and 555, that added together give a palindrome (575).

The spelling of 20555 in words is "twenty thousand, five hundred fifty-five".