20644738 has 4 divisors (see below), whose sum is σ = 30967110. Its totient is φ = 10322368.

The previous prime is 20644733. The next prime is 20644751. The reversal of 20644738 is 83744602.

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., 12159169 + 8485569 = 3487^2 + 2913^2 .

It is not an unprimeable number, because it can be changed into a prime (20644733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5161183 + ... + 5161186.

Almost surely, 2^20644738 is an apocalyptic number.

20644738 is a deficient number, since it is larger than the sum of its proper divisors (10322372).

20644738 is a wasteful number, since it uses less digits than its factorization.

20644738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10322371.

The product of its (nonzero) digits is 32256, while the sum is 34.

The square root of 20644738 is about 4543.6480937678. The cubic root of 20644738 is about 274.3277818403.

It can be divided in two parts, 206 and 44738, that added together give a palindrome (44944).

The spelling of 20644738 in words is "twenty million, six hundred forty-four thousand, seven hundred thirty-eight".