21868037856 has 480 divisors, whose sum is σ = 80370081792. Its totient is φ = 5688299520.

The previous prime is 21868037827. The next prime is 21868037869. The reversal of 21868037856 is 65873086812.

21868037856 is a `hidden beast` number, since 218 + 6 + 8 + 0 + 378 + 56 = 666.

It is a super-2 number, since 2×21868037856² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 9560745 + ... + 9563031.

Almost surely, 2^21868037856 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 21868037856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40185040896).

21868037856 is an abundant number, since it is smaller than the sum of its proper divisors (58502043936).

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

21868037856 is a wasteful number, since it uses less digits than its factorization.

21868037856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2364 (or 2347 counting only the distinct ones).

The product of its (nonzero) digits is 3870720, while the sum is 54.

The spelling of 21868037856 in words is "twenty-one billion, eight hundred sixty-eight million, thirty-seven thousand, eight hundred fifty-six".