221220000 has 180 divisors, whose sum is σ = 786755970. Its totient is φ = 58944000.

The previous prime is 221219989. The next prime is 221220007. The reversal of 221220000 is 22122.

It can be written as a sum of positive squares in 5 ways, for example, as 40908816 + 180311184 = 6396^2 + 13428^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (221220007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 179386 + ... + 180614.

Almost surely, 2^221220000 is an apocalyptic number.

221220000 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 221220000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (393377985).

221220000 is an abundant number, since it is smaller than the sum of its proper divisors (565535970).

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

221220000 is a wasteful number, since it uses less digits than its factorization.

221220000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1265 (or 1239 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 221220000 is about 14873.4663074886. The cubic root of 221220000 is about 604.7949126136.

Adding to 221220000 its reverse (22122), we get a palindrome (221242122).

Multiplying 221220000 by its reverse (22122), we get a square (4893828840000 = 2212200²).

221220000 divided by its reverse (22122) gives a 4-th power (10000 = 10⁴).

The spelling of 221220000 in words is "two hundred twenty-one million, two hundred twenty thousand".