221018220 has 192 divisors, whose sum is σ = 722964480. Its totient is φ = 56687040.

The previous prime is 221018219. The next prime is 221018261. The reversal of 221018220 is 22810122.

It is a happy number.

221018220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a junction number, because it is equal to n+sod(n) for n = 221018193 and 221018202.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1355859 + ... + 1356021.

It is an arithmetic number, because the mean of its divisors is an integer number (3765440).

Almost surely, 2^221018220 is an apocalyptic number.

221018220 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 221018220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (361482240).

221018220 is an abundant number, since it is smaller than the sum of its proper divisors (501946260).

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

221018220 is a wasteful number, since it uses less digits than its factorization.

221018220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224 (or 204 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 221018220 is about 14866.6815396039. The cubic root of 221018220 is about 604.6109740907.

Adding to 221018220 its reverse (22810122), we get a palindrome (243828342).

The spelling of 221018220 in words is "two hundred twenty-one million, eighteen thousand, two hundred twenty".