20043640 has 64 divisors (see below), whose sum is σ = 48016800. Its totient is φ = 7515648.

The previous prime is 20043623. The next prime is 20043641. The reversal of 20043640 is 4634002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20043641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42687 + ... + 43153.

Almost surely, 2^20043640 is an apocalyptic number.

20043640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20043640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24008400).

20043640 is an abundant number, since it is smaller than the sum of its proper divisors (27973160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20043640 is a wasteful number, since it uses less digits than its factorization.

20043640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544 (or 540 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 20043640 is about 4477.0123966771. The cubic root of 20043640 is about 271.6390468782.

Adding to 20043640 its reverse (4634002), we get a palindrome (24677642).

The spelling of 20043640 in words is "twenty million, forty-three thousand, six hundred forty".