20639744 has 26 divisors (see below), whose sum is σ = 41282640. Its totient is φ = 10317824.

The previous prime is 20639741. The next prime is 20639767. The reversal of 20639744 is 44793602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20639741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1577 + ... + 6615.

Almost surely, 2^20639744 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 20639744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20641320).

20639744 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

20639744 is an frugal number, since it uses more digits than its factorization.

20639744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5063 (or 5041 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 35.

The square root of 20639744 is about 4543.0985021239. The cubic root of 20639744 is about 274.3056599252.

The spelling of 20639744 in words is "twenty million, six hundred thirty-nine thousand, seven hundred forty-four".