21221212100 has 72 divisors (see below), whose sum is σ = 52880469600. Its totient is φ = 7310649600.

The previous prime is 21221212079. The next prime is 21221212109. The reversal of 21221212100 is 121212212.

It is not an unprimeable number, because it can be changed into a prime (21221212109) 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, 486785 + ... + 528584.

Almost surely, 2^21221212100 is an apocalyptic number.

21221212100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221212100 is an abundant number, since it is smaller than the sum of its proper divisors (31659257500).

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

21221212100 is a wasteful number, since it uses less digits than its factorization.

21221212100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1015413 (or 1015406 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21221212100 its reverse (121212212), we get a palindrome (21342424312).

The spelling of 21221212100 in words is "twenty-one billion, two hundred twenty-one million, two hundred twelve thousand, one hundred".