20428 has 6 divisors (see below), whose sum is σ = 35756. Its totient is φ = 10212.

The previous prime is 20411. The next prime is 20431. The reversal of 20428 is 82402.

It is a nialpdrome in base 14.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2550 + ... + 2557.

2²⁰⁴²⁸ is an apocalyptic number.

It is an amenable number.

20428 is a deficient number, since it is larger than the sum of its proper divisors (15328).

20428 is a wasteful number, since it uses less digits than its factorization.

20428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5111 (or 5109 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 20428 is about 142.9265545656. The cubic root of 20428 is about 27.3364395967.

It can be divided in two parts, 204 and 28, that added together give a palindrome (232).

The spelling of 20428 in words is "twenty thousand, four hundred twenty-eight".