221221001100 has 144 divisors (see below), whose sum is σ = 698510292480. Its totient is φ = 53609644800.

The previous prime is 221221001033. The next prime is 221221001101. The reversal of 221221001100 is 1100122122.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (221221001101) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 10281954 + ... + 10303446.

It is an arithmetic number, because the mean of its divisors is an integer number (4850765920).

Almost surely, 2^221221001100 is an apocalyptic number.

221221001100 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 221221001100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (349255146240).

221221001100 is an abundant number, since it is smaller than the sum of its proper divisors (477289291380).

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

221221001100 is a wasteful number, since it uses less digits than its factorization.

221221001100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24640 (or 24633 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 221221001100 its reverse (1100122122), we get a palindrome (222321123222).

The spelling of 221221001100 in words is "two hundred twenty-one billion, two hundred twenty-one million, one thousand, one hundred".