20428866 has 48 divisors (see below), whose sum is σ = 47401848. Its totient is φ = 6336000.

The previous prime is 20428843. The next prime is 20428909. The reversal of 20428866 is 66882402.

It can be written as a sum of positive squares in 4 ways, for example, as 19580625 + 848241 = 4425^2 + 921^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20428866.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30576 + ... + 31236.

Almost surely, 2^20428866 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20428866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23700924).

20428866 is an abundant number, since it is smaller than the sum of its proper divisors (26972982).

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

20428866 is a wasteful number, since it uses less digits than its factorization.

20428866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 787 (or 784 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 20428866 is about 4519.8303065491. The cubic root of 20428866 is about 273.3682588064.

The spelling of 20428866 in words is "twenty million, four hundred twenty-eight thousand, eight hundred sixty-six".