21856016871 has 12 divisors (see below), whose sum is σ = 33998248648. Its totient is φ = 13449856464.

The previous prime is 21856016803. The next prime is 21856016921. The reversal of 21856016871 is 17861065812.

21856016871 is a `hidden beast` number, since 2 + 1 + 8 + 560 + 1 + 6 + 87 + 1 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-21856016871 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21856116871) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 93401665 + ... + 93401898.

Almost surely, 2^21856016871 is an apocalyptic number.

21856016871 is a deficient number, since it is larger than the sum of its proper divisors (12142231777).

21856016871 is a wasteful number, since it uses less digits than its factorization.

21856016871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186803582 (or 186803579 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 45.

The spelling of 21856016871 in words is "twenty-one billion, eight hundred fifty-six million, sixteen thousand, eight hundred seventy-one".