221231220 has 48 divisors (see below), whose sum is σ = 707941248. Its totient is φ = 50567040.

The previous prime is 221231207. The next prime is 221231233. The reversal of 221231220 is 22132122.

It is a happy number.

221231220 is digitally balanced in base 3, 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 (221231207) and next prime (221231233).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 221231220.

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, 262951 + ... + 263790.

It is an arithmetic number, because the mean of its divisors is an integer number (14748776).

Almost surely, 2^221231220 is an apocalyptic number.

221231220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221231220 is an abundant number, since it is smaller than the sum of its proper divisors (486710028).

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

221231220 is a wasteful number, since it uses less digits than its factorization.

221231220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526760 (or 526758 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 221231220 is about 14873.8434844528. The cubic root of 221231220 is about 604.8051372531.

Adding to 221231220 its reverse (22132122), we get a palindrome (243363342).

The spelling of 221231220 in words is "two hundred twenty-one million, two hundred thirty-one thousand, two hundred twenty".