221206128 has 240 divisors, whose sum is σ = 703633536. Its totient is φ = 59304960.

The previous prime is 221206127. The next prime is 221206169. The reversal of 221206128 is 821602122.

It is a Cunningham number, because it is equal to 14873²-1.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 221206098 and 221206107.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221206123) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3301551 + ... + 3301617.

Almost surely, 2^221206128 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 221206128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (351816768).

221206128 is an abundant number, since it is smaller than the sum of its proper divisors (482427408).

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

221206128 is a wasteful number, since it uses less digits than its factorization.

221206128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 221206128 is about 14872.9999663820. Note that the first 4 decimals coincide. The cubic root of 221206128 is about 604.7822707633.

The spelling of 221206128 in words is "two hundred twenty-one million, two hundred six thousand, one hundred twenty-eight".