21021100100 has 432 divisors, whose sum is σ = 65398564224. Its totient is φ = 5687193600.

The previous prime is 21021100073. The next prime is 21021100127. The reversal of 21021100100 is 100112012.

It is an interprime number because it is at equal distance from previous prime (21021100073) and next prime (21021100127).

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 18718139 + ... + 18719261.

Almost surely, 2^21021100100 is an apocalyptic number.

21021100100 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 21021100100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32699282112).

21021100100 is an abundant number, since it is smaller than the sum of its proper divisors (44377464124).

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

21021100100 is a wasteful number, since it uses less digits than its factorization.

21021100100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1196 (or 1178 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21021100100 its reverse (100112012), we get a palindrome (21121212112).

It can be divided in two parts, 21021 and 100100, that added together give a palindrome (121121).

The spelling of 21021100100 in words is "twenty-one billion, twenty-one million, one hundred thousand, one hundred".