20244640 has 48 divisors (see below), whose sum is σ = 51512328. Its totient is φ = 7474176.

The previous prime is 20244617. The next prime is 20244641. The reversal of 20244640 is 4644202.

It can be written as a sum of positive squares in 4 ways, for example, as 16418704 + 3825936 = 4052^2 + 1956^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20244641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2787 + ... + 6946.

Almost surely, 2^20244640 is an apocalyptic number.

20244640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20244640 is an abundant number, since it is smaller than the sum of its proper divisors (31267688).

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

20244640 is a wasteful number, since it uses less digits than its factorization.

20244640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9761 (or 9753 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 20244640 is about 4499.4044050296. The cubic root of 20244640 is about 272.5440379968.

Adding to 20244640 its reverse (4644202), we get a palindrome (24888842).

The spelling of 20244640 in words is "twenty million, two hundred forty-four thousand, six hundred forty".