221211216 has 80 divisors (see below), whose sum is σ = 641625600. Its totient is φ = 72963072.

The previous prime is 221211209. The next prime is 221211223. The reversal of 221211216 is 612112122.

221211216 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (221211209) and next prime (221211223).

It is a Harshad number since it is a multiple of its sum of digits (18).

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 polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39265 + ... + 44543.

It is an arithmetic number, because the mean of its divisors is an integer number (8020320).

Almost surely, 2^221211216 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 221211216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (320812800).

221211216 is an abundant number, since it is smaller than the sum of its proper divisors (420414384).

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

221211216 is a wasteful number, since it uses less digits than its factorization.

221211216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5393 (or 5381 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 221211216 is about 14873.1710136070. The cubic root of 221211216 is about 604.7869076279.

Adding to 221211216 its reverse (612112122), we get a palindrome (833323338).

The spelling of 221211216 in words is "two hundred twenty-one million, two hundred eleven thousand, two hundred sixteen".