221787216 has 120 divisors (see below), whose sum is σ = 721195904. Its totient is φ = 62311680.

The previous prime is 221787193. The next prime is 221787227. The reversal of 221787216 is 612787122.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 59685 + ... + 63291.

Almost surely, 2^221787216 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 221787216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (360597952).

221787216 is an abundant number, since it is smaller than the sum of its proper divisors (499408688).

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

221787216 is a wasteful number, since it uses less digits than its factorization.

221787216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3689 (or 3680 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 221787216 is about 14892.5221503948. The cubic root of 221787216 is about 605.3113767235.

The spelling of 221787216 in words is "two hundred twenty-one million, seven hundred eighty-seven thousand, two hundred sixteen".