221021320 has 64 divisors (see below), whose sum is σ = 552867840. Its totient is φ = 78969600.

The previous prime is 221021299. The next prime is 221021323. The reversal of 221021320 is 23120122.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a self number, because there is not a number n which added to its sum of digits gives 221021320.

It is not an unprimeable number, because it can be changed into a prime (221021323) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9265 + ... + 22975.

It is an arithmetic number, because the mean of its divisors is an integer number (8638560).

Almost surely, 2^221021320 is an apocalyptic number.

221021320 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 221021320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (276433920).

221021320 is an abundant number, since it is smaller than the sum of its proper divisors (331846520).

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

221021320 is a wasteful number, since it uses less digits than its factorization.

221021320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13766 (or 13762 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 221021320 is about 14866.7857992237. The cubic root of 221021320 is about 604.6138008339.

Adding to 221021320 its reverse (23120122), we get a palindrome (244141442).

The spelling of 221021320 in words is "two hundred twenty-one million, twenty-one thousand, three hundred twenty".