20188138 has 4 divisors (see below), whose sum is σ = 30282210. Its totient is φ = 10094068.

The previous prime is 20188111. The next prime is 20188141. The reversal of 20188138 is 83188102.

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., 20187049 + 1089 = 4493^2 + 33^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5047033 + ... + 5047036.

Almost surely, 2^20188138 is an apocalyptic number.

20188138 is a deficient number, since it is larger than the sum of its proper divisors (10094072).

20188138 is a wasteful number, since it uses less digits than its factorization.

20188138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10094071.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 20188138 is about 4493.1211868811. The cubic root of 20188138 is about 272.2902484875.

The spelling of 20188138 in words is "twenty million, one hundred eighty-eight thousand, one hundred thirty-eight".