21010021200 has 360 divisors, whose sum is σ = 88229763648. Its totient is φ = 4519710720.

The previous prime is 21010021199. The next prime is 21010021211. The reversal of 21010021200 is 212001012.

It is a tau number, because it is divible by the number of its divisors (360).

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

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

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 71 ways as a sum of consecutive naturals, for example, 403879 + ... + 452921.

Almost surely, 2^21010021200 is an apocalyptic number.

21010021200 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 21010021200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44114881824).

21010021200 is an abundant number, since it is smaller than the sum of its proper divisors (67219742448).

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

21010021200 is a wasteful number, since it uses less digits than its factorization.

21010021200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49091 (or 49077 counting only the distinct ones).

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

Adding to 21010021200 its reverse (212001012), we get a palindrome (21222022212).

The spelling of 21010021200 in words is "twenty-one billion, ten million, twenty-one thousand, two hundred".