20236640 has 48 divisors (see below), whose sum is σ = 48444480. Its totient is φ = 7987200.

The previous prime is 20236639. The next prime is 20236651. The reversal of 20236640 is 4663202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11840 + ... + 13440.

It is an arithmetic number, because the mean of its divisors is an integer number (1009260).

Almost surely, 2^20236640 is an apocalyptic number.

20236640 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 20236640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24222240).

20236640 is an abundant number, since it is smaller than the sum of its proper divisors (28207840).

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

20236640 is a wasteful number, since it uses less digits than its factorization.

20236640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1695 (or 1687 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 20236640 is about 4498.5153106331. The cubic root of 20236640 is about 272.5081331916.

Adding to 20236640 its reverse (4663202), we get a palindrome (24899842).

The spelling of 20236640 in words is "twenty million, two hundred thirty-six thousand, six hundred forty".