20558 has 8 divisors (see below), whose sum is σ = 32520. Its totient is φ = 9720.

The previous prime is 20551. The next prime is 20563. The reversal of 20558 is 85502.

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

It is a super-3 number, since 3×20558³ = 26065366743336, which contains 333 as substring.

It is a Curzon number.

It is a plaindrome in base 11.

It is a nialpdrome in base 12.

It is a congruent number.

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, 233 + ... + 308.

It is an arithmetic number, because the mean of its divisors is an integer number (4065).

2²⁰⁵⁵⁸ is an apocalyptic number.

20558 is a deficient number, since it is larger than the sum of its proper divisors (11962).

20558 is a wasteful number, since it uses less digits than its factorization.

20558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 20558 is about 143.3806123575. The cubic root of 20558 is about 27.3943050306.

The spelling of 20558 in words is "twenty thousand, five hundred fifty-eight".