20209644 has 144 divisors (see below), whose sum is σ = 65228800. Its totient is φ = 5132160.

The previous prime is 20209633. The next prime is 20209649. The reversal of 20209644 is 44690202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20209649) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 101457 + ... + 101655.

Almost surely, 2^20209644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20209644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32614400).

20209644 is an abundant number, since it is smaller than the sum of its proper divisors (45019156).

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

20209644 is a wasteful number, since it uses less digits than its factorization.

20209644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260 (or 255 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 20209644 is about 4495.5137637427. The cubic root of 20209644 is about 272.3869025381.

Adding to 20209644 its reverse (44690202), we get a palindrome (64899846).

It can be divided in two parts, 2020 and 9644, that added together give a square (11664 = 108²).

The spelling of 20209644 in words is "twenty million, two hundred nine thousand, six hundred forty-four".