21865616136 has 480 divisors, whose sum is σ = 77228736000. Its totient is φ = 5580731520.

The previous prime is 21865616023. The next prime is 21865616137. The reversal of 21865616136 is 63161656812.

21865616136 is a `hidden beast` number, since 2 + 1 + 86 + 561 + 6 + 1 + 3 + 6 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21865616091 and 21865616100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21865616137) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 705342441 + ... + 705342471.

It is an arithmetic number, because the mean of its divisors is an integer number (160893200).

Almost surely, 2^21865616136 is an apocalyptic number.

21865616136 is a gapful number since it is divisible by the number (26) 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 21865616136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38614368000).

21865616136 is an abundant number, since it is smaller than the sum of its proper divisors (55363119864).

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

21865616136 is an equidigital number, since it uses as much as digits as its factorization.

21865616136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116 (or 56 counting only the distinct ones).

The product of its digits is 311040, while the sum is 45.

The spelling of 21865616136 in words is "twenty-one billion, eight hundred sixty-five million, six hundred sixteen thousand, one hundred thirty-six".