20440138 has 4 divisors (see below), whose sum is σ = 30660210. Its totient is φ = 10220068.

The previous prime is 20440111. The next prime is 20440151. The reversal of 20440138 is 83104402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83104402 = 2 ⋅41552201.

It can be written as a sum of positive squares in only one way, i.e., 18636489 + 1803649 = 4317^2 + 1343^2 .

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 an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5110033 + ... + 5110036.

Almost surely, 2^20440138 is an apocalyptic number.

20440138 is a deficient number, since it is larger than the sum of its proper divisors (10220072).

20440138 is a wasteful number, since it uses less digits than its factorization.

20440138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10220071.

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 20440138 is about 4521.0770840586. The cubic root of 20440138 is about 273.4185282054.

The spelling of 20440138 in words is "twenty million, four hundred forty thousand, one hundred thirty-eight".