21966228 has 72 divisors (see below), whose sum is σ = 59521280. Its totient is φ = 7085880.

The previous prime is 21966209. The next prime is 21966233. The reversal of 21966228 is 82266912.

It is a happy number.

21966228 is a `hidden beast` number, since 21 + 9 + 6 + 622 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

Its product of digits (20736) is a multiple of the sum of its prime divisors (36).

It is a junction number, because it is equal to n+sod(n) for n = 21966192 and 21966201.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 708573 + ... + 708603.

Almost surely, 2^21966228 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 21966228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29760640).

21966228 is an abundant number, since it is smaller than the sum of its proper divisors (37555052).

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

21966228 is an frugal number, since it uses more digits than its factorization.

21966228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68 (or 36 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 21966228 is about 4686.8142698426. The cubic root of 21966228 is about 280.0604801326.

The spelling of 21966228 in words is "twenty-one million, nine hundred sixty-six thousand, two hundred twenty-eight".