21200021010 has 216 divisors, whose sum is σ = 65271663756. Its totient is φ = 4760138880.

The previous prime is 21200021009. The next prime is 21200021027. The reversal of 21200021010 is 1012000212.

It can be written as a sum of positive squares in 2 ways, for example, as 21014271369 + 185749641 = 144963^2 + 13629^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21200020983 and 21200021001.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 15350520 + ... + 15351900.

Almost surely, 2^21200021010 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21200021010, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32635831878).

21200021010 is an abundant number, since it is smaller than the sum of its proper divisors (44071642746).

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

21200021010 is a wasteful number, since it uses less digits than its factorization.

21200021010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1526 (or 1457 counting only the distinct ones).

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

Adding to 21200021010 its reverse (1012000212), we get a palindrome (22212021222).

The spelling of 21200021010 in words is "twenty-one billion, two hundred million, twenty-one thousand, ten".