21011220000 has 360 divisors, whose sum is σ = 75398086764. Its totient is φ = 5548032000.

The previous prime is 21011219987. The next prime is 21011220019. The reversal of 21011220000 is 2211012.

It can be written as a sum of positive squares in 10 ways, for example, as 1963907856 + 19047312144 = 44316^2 + 138012^2 .

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 an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 20339484 + ... + 20340516.

Almost surely, 2^21011220000 is an apocalyptic number.

21011220000 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 21011220000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37699043382).

21011220000 is an abundant number, since it is smaller than the sum of its proper divisors (54386866764).

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

21011220000 is a wasteful number, since it uses less digits than its factorization.

21011220000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1182 (or 1156 counting only the distinct ones).

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

Adding to 21011220000 its reverse (2211012), we get a palindrome (21013431012).

The spelling of 21011220000 in words is "twenty-one billion, eleven million, two hundred twenty thousand".