21221201100 has 72 divisors (see below), whose sum is σ = 66981837888. Its totient is φ = 5144532800.

The previous prime is 21221201087. The next prime is 21221201117. The reversal of 21221201100 is 110212212.

It is a super-2 number, since 2×21221201100² (a number of 21 digits) contains 22 as substring.

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

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 3212034 + ... + 3218633.

It is an arithmetic number, because the mean of its divisors is an integer number (930303304).

Almost surely, 2^21221201100 is an apocalyptic number.

21221201100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21221201100 is an abundant number, since it is smaller than the sum of its proper divisors (45760636788).

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

21221201100 is a wasteful number, since it uses less digits than its factorization.

21221201100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6430695 (or 6430688 counting only the distinct ones).

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

Adding to 21221201100 its reverse (110212212), we get a palindrome (21331413312).

The spelling of 21221201100 in words is "twenty-one billion, two hundred twenty-one million, two hundred one thousand, one hundred".