20640344 has 32 divisors (see below), whose sum is σ = 40986000. Its totient is φ = 9727872.

The previous prime is 20640331. The next prime is 20640391. The reversal of 20640344 is 44304602.

It is a happy number.

It is a super-3 number, since 3×20640344³ (a number of 23 digits) contains 333 as substring.

It is a congruent 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 in 7 ways as a sum of consecutive naturals, for example, 8942 + ... + 11010.

Almost surely, 2^20640344 is an apocalyptic number.

It is an amenable number.

20640344 is a deficient number, since it is larger than the sum of its proper divisors (20345656).

20640344 is a wasteful number, since it uses less digits than its factorization.

20640344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2147 (or 2143 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 23.

The square root of 20640344 is about 4543.1645358714. The cubic root of 20640344 is about 274.3083179330.

Adding to 20640344 its reverse (44304602), we get a palindrome (64944946).

The spelling of 20640344 in words is "twenty million, six hundred forty thousand, three hundred forty-four".