21105084856 has 8 divisors (see below), whose sum is σ = 39572034120. Its totient is φ = 10552542424.

The previous prime is 21105084853. The next prime is 21105084857. The reversal of 21105084856 is 65848050112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105084851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1319067796 + ... + 1319067811.

It is an arithmetic number, because the mean of its divisors is an integer number (4946504265).

Almost surely, 2^21105084856 is an apocalyptic number.

It is an amenable number.

21105084856 is a deficient number, since it is larger than the sum of its proper divisors (18466949264).

21105084856 is a wasteful number, since it uses less digits than its factorization.

21105084856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2638135613 (or 2638135609 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 40.

The spelling of 21105084856 in words is "twenty-one billion, one hundred five million, eighty-four thousand, eight hundred fifty-six".