21210200100 has 54 divisors (see below), whose sum is σ = 66482196690. Its totient is φ = 5656053120.

The previous prime is 21210200071. The next prime is 21210200107. The reversal of 21210200100 is 100201212.

It can be written as a sum of positive squares in 3 ways, for example, as 4883493924 + 16326706176 = 69882^2 + 127776^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21210200107) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11782545 + ... + 11784344.

Almost surely, 2^21210200100 is an apocalyptic number.

21210200100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210200100 is an abundant number, since it is smaller than the sum of its proper divisors (45271996590).

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

21210200100 is a wasteful number, since it uses less digits than its factorization.

21210200100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23566909 (or 23566899 counting only the distinct ones).

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

Adding to 21210200100 its reverse (100201212), we get a palindrome (21310401312).

The spelling of 21210200100 in words is "twenty-one billion, two hundred ten million, two hundred thousand, one hundred".