20728686 has 32 divisors (see below), whose sum is σ = 45600768. Its totient is φ = 6229440.

The previous prime is 20728637. The next prime is 20728691. The reversal of 20728686 is 68682702.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7146 + ... + 9618.

It is an arithmetic number, because the mean of its divisors is an integer number (1425024).

Almost surely, 2^20728686 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20728686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22800384).

20728686 is an abundant number, since it is smaller than the sum of its proper divisors (24872082).

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

20728686 is a wasteful number, since it uses less digits than its factorization.

20728686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2616.

The product of its (nonzero) digits is 64512, while the sum is 39.

The square root of 20728686 is about 4552.8766730497. The cubic root of 20728686 is about 274.6991133342.

The spelling of 20728686 in words is "twenty million, seven hundred twenty-eight thousand, six hundred eighty-six".