20909728 has 96 divisors (see below), whose sum is σ = 52617600. Its totient is φ = 7990272.

The previous prime is 20909723. The next prime is 20909741. The reversal of 20909728 is 82790902.

It is not an unprimeable number, because it can be changed into a prime (20909723) 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, 1100503 + ... + 1100521.

It is an arithmetic number, because the mean of its divisors is an integer number (548100).

Almost surely, 2^20909728 is an apocalyptic number.

20909728 is a gapful number since it is divisible by the number (28) 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 20909728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26308800).

20909728 is an abundant number, since it is smaller than the sum of its proper divisors (31707872).

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

20909728 is an equidigital number, since it uses as much as digits as its factorization.

20909728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 20909728 is about 4572.7156045396. The cubic root of 20909728 is about 275.4965266475.

The spelling of 20909728 in words is "twenty million, nine hundred nine thousand, seven hundred twenty-eight".