20390644 has 12 divisors (see below), whose sum is σ = 35726404. Its totient is φ = 10183104.

The previous prime is 20390641. The next prime is 20390651. The reversal of 20390644 is 44609302.

It can be written as a sum of positive squares in 2 ways, for example, as 7344100 + 13046544 = 2710^2 + 3612^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20390641) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 1432 + ... + 6544.

Almost surely, 2^20390644 is an apocalyptic number.

It is an amenable number.

20390644 is a deficient number, since it is larger than the sum of its proper divisors (15335760).

20390644 is a wasteful number, since it uses less digits than its factorization.

20390644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6114 (or 6112 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 20390644 is about 4515.6000708654. The cubic root of 20390644 is about 273.1976635191.

Adding to 20390644 its reverse (44609302), we get a palindrome (64999946).

The spelling of 20390644 in words is "twenty million, three hundred ninety thousand, six hundred forty-four".