221555000 has 80 divisors (see below), whose sum is σ = 527081280. Its totient is φ = 87264000.

The previous prime is 221554973. The next prime is 221555017. The reversal of 221555000 is 555122.

It is a Harshad number since it is a multiple of its sum of digits (20).

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 19 ways as a sum of consecutive naturals, for example, 364697 + ... + 365303.

It is an arithmetic number, because the mean of its divisors is an integer number (6588516).

Almost surely, 2^221555000 is an apocalyptic number.

221555000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221555000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (263540640).

221555000 is an abundant number, since it is smaller than the sum of its proper divisors (305526280).

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

221555000 is an equidigital number, since it uses as much as digits as its factorization.

221555000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 706 (or 687 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 20.

The square root of 221555000 is about 14884.7237125853. The cubic root of 221555000 is about 605.1000449265.

The spelling of 221555000 in words is "two hundred twenty-one million, five hundred fifty-five thousand".