21115222500 has 240 divisors, whose sum is σ = 65750952960. Its totient is φ = 5256720000.

The previous prime is 21115222477. The next prime is 21115222501. The reversal of 21115222500 is 522251112.

It is not an unprimeable number, because it can be changed into a prime (21115222501) by changing a digit.

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 79 ways as a sum of consecutive naturals, for example, 10116457 + ... + 10118543.

It is an arithmetic number, because the mean of its divisors is an integer number (273962304).

Almost surely, 2^21115222500 is an apocalyptic number.

21115222500 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 21115222500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32875476480).

21115222500 is an abundant number, since it is smaller than the sum of its proper divisors (44635730460).

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

21115222500 is a wasteful number, since it uses less digits than its factorization.

21115222500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2204 (or 2187 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 21.

Adding to 21115222500 its reverse (522251112), we get a palindrome (21637473612).

The spelling of 21115222500 in words is "twenty-one billion, one hundred fifteen million, two hundred twenty-two thousand, five hundred".