21101020800 has 192 divisors, whose sum is σ = 69599667360. Its totient is φ = 5618995200.

The previous prime is 21101020799. The next prime is 21101020807. The reversal of 21101020800 is 802010112.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21101020800.

It is not an unprimeable number, because it can be changed into a prime (21101020807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10491795 + ... + 10493805.

Almost surely, 2^21101020800 is an apocalyptic number.

21101020800 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 21101020800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34799833680).

21101020800 is an abundant number, since it is smaller than the sum of its proper divisors (48498646560).

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

21101020800 is a wasteful number, since it uses less digits than its factorization.

21101020800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3131 (or 3114 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21101020800 its reverse (802010112), we get a palindrome (21903030912).

The spelling of 21101020800 in words is "twenty-one billion, one hundred one million, twenty thousand, eight hundred".