21221100000 has 864 divisors, whose sum is σ = 85221732960. Its totient is φ = 4976640000.

The previous prime is 21221099987. The next prime is 21221100007. The reversal of 21221100000 is 112212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221100007) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 290699964 + ... + 290700036.

It is an arithmetic number, because the mean of its divisors is an integer number (98636265).

Almost surely, 2^21221100000 is an apocalyptic number.

21221100000 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 21221100000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42610866480).

21221100000 is an abundant number, since it is smaller than the sum of its proper divisors (64000632960).

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

21221100000 is a wasteful number, since it uses less digits than its factorization.

21221100000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150 (or 119 counting only the distinct ones).

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

Adding to 21221100000 its reverse (112212), we get a palindrome (21221212212).

The spelling of 21221100000 in words is "twenty-one billion, two hundred twenty-one million, one hundred thousand".