221221220 has 24 divisors (see below), whose sum is σ = 506798208. Its totient is φ = 80444000.

The previous prime is 221221219. The next prime is 221221243. The reversal of 221221220 is 22122122.

221221220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 221221195 and 221221204.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502556 + ... + 502995.

It is an arithmetic number, because the mean of its divisors is an integer number (21116592).

Almost surely, 2^221221220 is an apocalyptic number.

221221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221221220 is an abundant number, since it is smaller than the sum of its proper divisors (285576988).

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

221221220 is a wasteful number, since it uses less digits than its factorization.

221221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1005571 (or 1005569 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 221221220 is about 14873.5073200641. The cubic root of 221221220 is about 604.7960244004.

Adding to 221221220 its reverse (22122122), we get a palindrome (243343342).

It can be divided in two parts, 2212 and 21220, that added together give a palindrome (23432).

The spelling of 221221220 in words is "two hundred twenty-one million, two hundred twenty-one thousand, two hundred twenty".