20138 has 4 divisors (see below), whose sum is σ = 30210. Its totient is φ = 10068.

The previous prime is 20129. The next prime is 20143. The reversal of 20138 is 83102.

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

It can be written as a sum of positive squares in only one way, i.e., 18769 + 1369 = 137^2 + 37^2 .

It is an Ulam number.

It is a Curzon number.

It is a plaindrome in base 7.

It is a nialpdrome in base 13.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5033 + ... + 5036.

2²⁰¹³⁸ is an apocalyptic number.

20138 is a deficient number, since it is larger than the sum of its proper divisors (10072).

20138 is a wasteful number, since it uses less digits than its factorization.

20138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10071.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 20138 is about 141.9084211737. The cubic root of 20138 is about 27.2064647264.

The spelling of 20138 in words is "twenty thousand, one hundred thirty-eight".