21438873856 has 36 divisors (see below), whose sum is σ = 44174470144. Its totient is φ = 10373644800.

The previous prime is 21438873853. The next prime is 21438873857. The reversal of 21438873856 is 65837883412.

It is a junction number, because it is equal to n+sod(n) for n = 21438873797 and 21438873806.

It is not an unprimeable number, because it can be changed into a prime (21438873853) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1342800 + ... + 1358671.

Almost surely, 2^21438873856 is an apocalyptic number.

It is an amenable number.

21438873856 is an abundant number, since it is smaller than the sum of its proper divisors (22735596288).

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

21438873856 is an equidigital number, since it uses as much as digits as its factorization.

21438873856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2701518 (or 2701504 counting only the distinct ones).

The product of its digits is 7741440, while the sum is 55.

The spelling of 21438873856 in words is "twenty-one billion, four hundred thirty-eight million, eight hundred seventy-three thousand, eight hundred fifty-six".