20455 has 4 divisors (see below), whose sum is σ = 24552. Its totient is φ = 16360.

The previous prime is 20443. The next prime is 20477. The reversal of 20455 is 55402.

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: 55402 = 2 ⋅27701.

It is not a de Polignac number, because 20455 - 2⁷ = 20327 is a prime.

It is an Ulam number.

It is a Duffinian number.

20455 is a lucky number.

It is a nialpdrome in base 14.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2041 + ... + 2050.

It is an arithmetic number, because the mean of its divisors is an integer number (6138).

2²⁰⁴⁵⁵ is an apocalyptic number.

20455 is a deficient number, since it is larger than the sum of its proper divisors (4097).

20455 is an equidigital number, since it uses as much as digits as its factorization.

20455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4096.

The product of its (nonzero) digits is 200, while the sum is 16.

The square root of 20455 is about 143.0209774823. The cubic root of 20455 is about 27.3484779580.

Adding to 20455 its reverse (55402), we get a palindrome (75857).

The spelling of 20455 in words is "twenty thousand, four hundred fifty-five".