20728220 has 12 divisors (see below), whose sum is σ = 43529304. Its totient is φ = 8291280.

The previous prime is 20728217. The next prime is 20728229. The reversal of 20728220 is 2282702.

It is a happy number.

It is a hoax number, since the sum of its digits (23) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 518186 + ... + 518225.

It is an arithmetic number, because the mean of its divisors is an integer number (3627442).

Almost surely, 2^20728220 is an apocalyptic number.

20728220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20728220 is an abundant number, since it is smaller than the sum of its proper divisors (22801084).

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

20728220 is a wasteful number, since it uses less digits than its factorization.

20728220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1036420 (or 1036418 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 23.

The square root of 20728220 is about 4552.8254963264. The cubic root of 20728220 is about 274.6970548222.

The spelling of 20728220 in words is "twenty million, seven hundred twenty-eight thousand, two hundred twenty".