221021220100 has 72 divisors (see below), whose sum is σ = 488964719880. Its totient is φ = 86687278080.

The previous prime is 221021220071. The next prime is 221021220109. The reversal of 221021220100 is 1022120122.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 136451927236 + 84569292864 = 369394^2 + 290808^2 .

It is not an unprimeable number, because it can be changed into a prime (221021220109) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9279006 + ... + 9302794.

It is an arithmetic number, because the mean of its divisors is an integer number (6791176665).

Almost surely, 2^221021220100 is an apocalyptic number.

221021220100 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 221021220100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (244482359940).

221021220100 is an abundant number, since it is smaller than the sum of its proper divisors (267943499780).

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

221021220100 is a wasteful number, since it uses less digits than its factorization.

221021220100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25609 (or 25602 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 221021220100 its reverse (1022120122), we get a palindrome (222043340222).

The spelling of 221021220100 in words is "two hundred twenty-one billion, twenty-one million, two hundred twenty thousand, one hundred".