21806222 has 16 divisors (see below), whose sum is σ = 33363792. Its totient is φ = 10686720.

The previous prime is 21806207. The next prime is 21806227. The reversal of 21806222 is 22260812.

It is a super-4 number, since 4×21806222⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21806227) 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 7 ways as a sum of consecutive naturals, for example, 47072 + ... + 47532.

It is an arithmetic number, because the mean of its divisors is an integer number (2085237).

Almost surely, 2^21806222 is an apocalyptic number.

21806222 is a deficient number, since it is larger than the sum of its proper divisors (11557570).

21806222 is a wasteful number, since it uses less digits than its factorization.

21806222 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 883.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21806222 is about 4669.7132674287. The cubic root of 21806222 is about 279.3788185029.

The spelling of 21806222 in words is "twenty-one million, eight hundred six thousand, two hundred twenty-two".