21111222100 has 72 divisors (see below), whose sum is σ = 46178134688. Its totient is φ = 8377084800.

The previous prime is 21111222091. The next prime is 21111222113. The reversal of 21111222100 is 122211112.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13218502 + ... + 13220098.

Almost surely, 2^21111222100 is an apocalyptic number.

21111222100 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 21111222100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23089067344).

21111222100 is an abundant number, since it is smaller than the sum of its proper divisors (25066912588).

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

21111222100 is a wasteful number, since it uses less digits than its factorization.

21111222100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2585 (or 2578 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21111222100 its reverse (122211112), we get a palindrome (21233433212).

The spelling of 21111222100 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-two thousand, one hundred".