221212320 has 96 divisors (see below), whose sum is σ = 796376448. Its totient is φ = 50562048.

The previous prime is 221212309. The next prime is 221212333. The reversal of 221212320 is 23212122.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

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 221212320.

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, 29559 + ... + 36278.

It is an arithmetic number, because the mean of its divisors is an integer number (8295588).

Almost surely, 2^221212320 is an apocalyptic number.

221212320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221212320 is an abundant number, since it is smaller than the sum of its proper divisors (575164128).

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

221212320 is a wasteful number, since it uses less digits than its factorization.

221212320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65862 (or 65854 counting only the distinct ones).

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

The square root of 221212320 is about 14873.2081273678. The cubic root of 221212320 is about 604.7879137306.

Adding to 221212320 its reverse (23212122), we get a palindrome (244424442).

The spelling of 221212320 in words is "two hundred twenty-one million, two hundred twelve thousand, three hundred twenty".