20905728 has 72 divisors (see below), whose sum is σ = 56316288. Its totient is φ = 6884352.

The previous prime is 20905727. The next prime is 20905747. The reversal of 20905728 is 82750902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20905727) 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, 125101 + ... + 125267.

Almost surely, 2^20905728 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 20905728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28158144).

20905728 is an abundant number, since it is smaller than the sum of its proper divisors (35410560).

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

20905728 is a wasteful number, since it uses less digits than its factorization.

20905728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 349 (or 335 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 33.

The square root of 20905728 is about 4572.2782067586. The cubic root of 20905728 is about 275.4789581680.

The spelling of 20905728 in words is "twenty million, nine hundred five thousand, seven hundred twenty-eight".