20640044 has 6 divisors (see below), whose sum is σ = 36120084. Its totient is φ = 10320020.

The previous prime is 20640019. The next prime is 20640047. The reversal of 20640044 is 44004602.

It is a super-2 number, since 2×20640044² = 852022832643872, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20639998 and 20640025.

It is not an unprimeable number, because it can be changed into a prime (20640047) 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 as a sum of consecutive naturals, namely, 2580002 + ... + 2580009.

It is an arithmetic number, because the mean of its divisors is an integer number (6020014).

Almost surely, 2^20640044 is an apocalyptic number.

It is an amenable number.

20640044 is a deficient number, since it is larger than the sum of its proper divisors (15480040).

20640044 is a wasteful number, since it uses less digits than its factorization.

20640044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5160015 (or 5160013 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 20640044 is about 4543.1315191176. The cubic root of 20640044 is about 274.3069889355.

Adding to 20640044 its reverse (44004602), we get a palindrome (64644646).

It can be divided in two parts, 2064004 and 4, that multiplied together give a triangular number (8256016 = T₄₀₆₃).

The spelling of 20640044 in words is "twenty million, six hundred forty thousand, forty-four".