21221220222100 has 72 divisors (see below), whose sum is σ = 46872711128096. Its totient is φ = 8337247920000.

The previous prime is 21221220222071. The next prime is 21221220222149. The reversal of 21221220222100 is 122202212212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1697815 + ... + 6732385.

Almost surely, 2^{21221220222100} is an apocalyptic number.

21221220222100 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 21221220222100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23436355564048).

21221220222100 is an abundant number, since it is smaller than the sum of its proper divisors (25651490905996).

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

21221220222100 is a wasteful number, since it uses less digits than its factorization.

21221220222100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5035337 (or 5035330 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 19.

Adding to 21221220222100 its reverse (122202212212), we get a palindrome (21343422434312).

The spelling of 21221220222100 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred twenty-two thousand, one hundred".