221809806 has 64 divisors (see below), whose sum is σ = 514080000. Its totient is φ = 70803936.

The previous prime is 221809793. The next prime is 221809807. The reversal of 221809806 is 608908122.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221809807) 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 31 ways as a sum of consecutive naturals, for example, 217165 + ... + 218183.

It is an arithmetic number, because the mean of its divisors is an integer number (8032500).

Almost surely, 2^221809806 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221809806, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (257040000).

221809806 is an abundant number, since it is smaller than the sum of its proper divisors (292270194).

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

221809806 is a wasteful number, since it uses less digits than its factorization.

221809806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1198 (or 1192 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 221809806 is about 14893.2805654094. The cubic root of 221809806 is about 605.3319272313.

The spelling of 221809806 in words is "two hundred twenty-one million, eight hundred nine thousand, eight hundred six".