21311986500 has 432 divisors, whose sum is σ = 82341342720. Its totient is φ = 4614019200.

The previous prime is 21311986477. The next prime is 21311986513. The reversal of 21311986500 is 568911312.

21311986500 is a `hidden beast` number, since 2 + 131 + 19 + 8 + 6 + 500 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

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 143 ways as a sum of consecutive naturals, for example, 4186957 + ... + 4192043.

It is an arithmetic number, because the mean of its divisors is an integer number (190604960).

Almost surely, 2^21311986500 is an apocalyptic number.

21311986500 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 21311986500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41170671360).

21311986500 is an abundant number, since it is smaller than the sum of its proper divisors (61029356220).

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

21311986500 is a wasteful number, since it uses less digits than its factorization.

21311986500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5145 (or 5123 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The spelling of 21311986500 in words is "twenty-one billion, three hundred eleven million, nine hundred eighty-six thousand, five hundred".