21001100000 has 72 divisors (see below), whose sum is σ = 51679332936. Its totient is φ = 8400400000.

The previous prime is 21001099967. The next prime is 21001100017. The reversal of 21001100000 is 110012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (5).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5006 + ... + 205005.

It is an arithmetic number, because the mean of its divisors is an integer number (717768513).

Almost surely, 2^21001100000 is an apocalyptic number.

21001100000 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 21001100000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25839666468).

21001100000 is an abundant number, since it is smaller than the sum of its proper divisors (30678232936).

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

21001100000 is an frugal number, since it uses more digits than its factorization.

21001100000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210046 (or 210018 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 5.

Adding to 21001100000 its reverse (110012), we get a palindrome (21001210012).

The spelling of 21001100000 in words is "twenty-one billion, one million, one hundred thousand".