21850705856 has 28 divisors (see below), whose sum is σ = 49554280368. Its totient is φ = 9364588032.

The previous prime is 21850705843. The next prime is 21850705867. The reversal of 21850705856 is 65850705812.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (28).

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 21850705856.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 24386501 + ... + 24387396.

Almost surely, 2^21850705856 is an apocalyptic number.

It is an amenable number.

21850705856 is an abundant number, since it is smaller than the sum of its proper divisors (27703574512).

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

21850705856 is an equidigital number, since it uses as much as digits as its factorization.

21850705856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48773916 (or 48773906 counting only the distinct ones).

The product of its (nonzero) digits is 672000, while the sum is 47.

The spelling of 21850705856 in words is "twenty-one billion, eight hundred fifty million, seven hundred five thousand, eight hundred fifty-six".