21287927808 has 228 divisors, whose sum is σ = 70338343920. Its totient is φ = 6077546496.

The previous prime is 21287927797. The next prime is 21287927813. The reversal of 21287927808 is 80872978212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16514428 + ... + 16515716.

Almost surely, 2^21287927808 is an apocalyptic number.

21287927808 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21287927808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35169171960).

21287927808 is an abundant number, since it is smaller than the sum of its proper divisors (49050416112).

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

21287927808 is an frugal number, since it uses more digits than its factorization.

21287927808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1338 (or 1301 counting only the distinct ones).

The product of its (nonzero) digits is 1806336, while the sum is 54.

The spelling of 21287927808 in words is "twenty-one billion, two hundred eighty-seven million, nine hundred twenty-seven thousand, eight hundred eight".