21221223100 has 144 divisors (see below), whose sum is σ = 57482320896. Its totient is φ = 6606432000.

The previous prime is 21221223071. The next prime is 21221223103. The reversal of 21221223100 is 132212212.

It is a happy number.

It is a super-2 number, since 2×21221223100² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221223103) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12188230 + ... + 12189970.

It is an arithmetic number, because the mean of its divisors is an integer number (399182784).

Almost surely, 2^21221223100 is an apocalyptic number.

21221223100 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 21221223100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28741160448).

21221223100 is an abundant number, since it is smaller than the sum of its proper divisors (36261097796).

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

21221223100 is a wasteful number, since it uses less digits than its factorization.

21221223100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3356 (or 3349 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21221223100 its reverse (132212212), we get a palindrome (21353435312).

The spelling of 21221223100 in words is "twenty-one billion, two hundred twenty-one million, two hundred twenty-three thousand, one hundred".