20578 has 4 divisors (see below), whose sum is σ = 30870. Its totient is φ = 10288.

The previous prime is 20563. The next prime is 20593. The reversal of 20578 is 87502.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (20563) and next prime (20593).

It can be written as a sum of positive squares in only one way, i.e., 13689 + 6889 = 117^2 + 83^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a nialpdrome in base 12.

It is an unprimeable 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 as a sum of consecutive naturals, namely, 5143 + ... + 5146.

2²⁰⁵⁷⁸ is an apocalyptic number.

20578 is a deficient number, since it is larger than the sum of its proper divisors (10292).

20578 is a wasteful number, since it uses less digits than its factorization.

20578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10291.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 20578 is about 143.4503398393. The cubic root of 20578 is about 27.4031857343.

The spelling of 20578 in words is "twenty thousand, five hundred seventy-eight".