20639938 has 48 divisors (see below), whose sum is σ = 37490040. Its totient is φ = 8476160.

The previous prime is 20639923. The next prime is 20639939. The reversal of 20639938 is 83993602.

It can be written as a sum of positive squares in 4 ways, for example, as 20638849 + 1089 = 4543^2 + 33^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20639938.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20639939) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 119220 + ... + 119392.

Almost surely, 2^20639938 is an apocalyptic number.

20639938 is a deficient number, since it is larger than the sum of its proper divisors (16850102).

20639938 is a wasteful number, since it uses less digits than its factorization.

20639938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 232 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 20639938 is about 4543.1198531406. The cubic root of 20639938 is about 274.3065193534.

It can be divided in two parts, 206 and 39938, that multiplied together give a palindrome (8227228).

The spelling of 20639938 in words is "twenty million, six hundred thirty-nine thousand, nine hundred thirty-eight".