21200102100 has 108 divisors (see below), whose sum is σ = 66554149116. Its totient is φ = 5644546560.

The previous prime is 21200102081. The next prime is 21200102159. The reversal of 21200102100 is 120100212.

It can be written as a sum of positive squares in 6 ways, for example, as 22867524 + 21177234576 = 4782^2 + 145524^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 569664 + ... + 605736.

Almost surely, 2^21200102100 is an apocalyptic number.

21200102100 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 21200102100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33277074558).

21200102100 is an abundant number, since it is smaller than the sum of its proper divisors (45354047016).

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

21200102100 is a wasteful number, since it uses less digits than its factorization.

21200102100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36746 (or 36736 counting only the distinct ones).

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

Adding to 21200102100 its reverse (120100212), we get a palindrome (21320202312).

The spelling of 21200102100 in words is "twenty-one billion, two hundred million, one hundred two thousand, one hundred".