21539438006784 has 320 divisors, whose sum is σ = 62806482984960. Its totient is φ = 6534425640960.

The previous prime is 21539438006783. The next prime is 21539438006813. The reversal of 21539438006784 is 48760083493512.

It is not an unprimeable number, because it can be changed into a prime (21539438006783) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123857557 + ... + 124031339.

It is an arithmetic number, because the mean of its divisors is an integer number (196270259328).

It is a 1-persistent number, because it is pandigital, but 2⋅21539438006784 = 43078876013568 is not.

Almost surely, 2^{21539438006784} is an apocalyptic number.

21539438006784 is a gapful number since it is divisible by the number (24) 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 21539438006784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31403241492480).

21539438006784 is an abundant number, since it is smaller than the sum of its proper divisors (41267044978176).

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

21539438006784 is a wasteful number, since it uses less digits than its factorization.

21539438006784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173991 (or 173975 counting only the distinct ones).

The product of its (nonzero) digits is 34836480, while the sum is 60.

The spelling of 21539438006784 in words is "twenty-one trillion, five hundred thirty-nine billion, four hundred thirty-eight million, six thousand, seven hundred eighty-four".