20817228 has 12 divisors (see below), whose sum is σ = 48573560. Its totient is φ = 6939072.

The previous prime is 20817221. The next prime is 20817229. The reversal of 20817228 is 82271802.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 20817195 and 20817204.

It is not an unprimeable number, because it can be changed into a prime (20817221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 867373 + ... + 867396.

Almost surely, 2^20817228 is an apocalyptic number.

It is an amenable number.

20817228 is an abundant number, since it is smaller than the sum of its proper divisors (27756332).

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

20817228 is a wasteful number, since it uses less digits than its factorization.

20817228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1734776 (or 1734774 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 20817228 is about 4562.5900539058. The cubic root of 20817228 is about 275.0896809436.

The spelling of 20817228 in words is "twenty million, eight hundred seventeen thousand, two hundred twenty-eight".