21226806 has 32 divisors (see below), whose sum is σ = 47882880. Its totient is φ = 6968808.

The previous prime is 21226771. The next prime is 21226823. The reversal of 21226806 is 60862212.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21226806.

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 15 ways as a sum of consecutive naturals, for example, 685 + ... + 6551.

It is an arithmetic number, because the mean of its divisors is an integer number (1496340).

Almost surely, 2^21226806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21226806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23941440).

21226806 is an abundant number, since it is smaller than the sum of its proper divisors (26656074).

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

21226806 is a wasteful number, since it uses less digits than its factorization.

21226806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5945 (or 5939 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 21226806 is about 4607.2557992801. The cubic root of 21226806 is about 276.8821021640.

The spelling of 21226806 in words is "twenty-one million, two hundred twenty-six thousand, eight hundred six".