221312220 has 24 divisors (see below), whose sum is σ = 619674384. Its totient is φ = 59016576.

The previous prime is 221312191. The next prime is 221312243. The reversal of 221312220 is 22213122.

It is a happy number.

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 221312220.

It is a congruent number.

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, 1844209 + ... + 1844328.

It is an arithmetic number, because the mean of its divisors is an integer number (25819766).

Almost surely, 2^221312220 is an apocalyptic number.

221312220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221312220 is an abundant number, since it is smaller than the sum of its proper divisors (398362164).

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

221312220 is a wasteful number, since it uses less digits than its factorization.

221312220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3688549 (or 3688547 counting only the distinct ones).

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

The square root of 221312220 is about 14876.5661360409. The cubic root of 221312220 is about 604.8789412404.

Adding to 221312220 its reverse (22213122), we get a palindrome (243525342).

The spelling of 221312220 in words is "two hundred twenty-one million, three hundred twelve thousand, two hundred twenty".