21021200100 has 54 divisors (see below), whose sum is σ = 65889786690. Its totient is φ = 5605653120.

The previous prime is 21021200089. The next prime is 21021200141. The reversal of 21021200100 is 100212012.

It can be written as a sum of positive squares in 3 ways, for example, as 314565696 + 20706634404 = 17736^2 + 143898^2 .

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11677545 + ... + 11679344.

It is an arithmetic number, because the mean of its divisors is an integer number (1220181235).

Almost surely, 2^21021200100 is an apocalyptic number.

21021200100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021200100 is an abundant number, since it is smaller than the sum of its proper divisors (44868586590).

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

21021200100 is a wasteful number, since it uses less digits than its factorization.

21021200100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23356909 (or 23356899 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21021200100 its reverse (100212012), we get a palindrome (21121412112).

The spelling of 21021200100 in words is "twenty-one billion, twenty-one million, two hundred thousand, one hundred".