21841981236 has 96 divisors (see below), whose sum is σ = 58010198400. Its totient is φ = 7103255040.

The previous prime is 21841981201. The next prime is 21841981237. The reversal of 21841981236 is 63218914812.

21841981236 is a `hidden beast` number, since 218 + 419 + 8 + 12 + 3 + 6 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21841981191 and 21841981200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21841981237) 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 31 ways as a sum of consecutive naturals, for example, 5148076 + ... + 5152316.

It is an arithmetic number, because the mean of its divisors is an integer number (604272900).

Almost surely, 2^21841981236 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21841981236, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29005099200).

21841981236 is an abundant number, since it is smaller than the sum of its proper divisors (36168217164).

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

21841981236 is a wasteful number, since it uses less digits than its factorization.

21841981236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5406 (or 5398 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The spelling of 21841981236 in words is "twenty-one billion, eight hundred forty-one million, nine hundred eighty-one thousand, two hundred thirty-six".