21591379803798 has 128 divisors (see below), whose sum is σ = 56752530508800. Its totient is φ = 5953469711616.

The previous prime is 21591379803781. The next prime is 21591379803809. The reversal of 21591379803798 is 89730897319512.

21591379803798 is a `hidden beast` number, since 2 + 1 + 5 + 91 + 379 + 80 + 3 + 7 + 98 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 23143765 + ... + 24058607.

It is an arithmetic number, because the mean of its divisors is an integer number (443379144600).

Almost surely, 2^{21591379803798} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21591379803798, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28376265254400).

21591379803798 is an abundant number, since it is smaller than the sum of its proper divisors (35161150705002).

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

21591379803798 is a wasteful number, since it uses less digits than its factorization.

21591379803798 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 917043 (or 917037 counting only the distinct ones).

The product of its (nonzero) digits is 205752960, while the sum is 72.

The spelling of 21591379803798 in words is "twenty-one trillion, five hundred ninety-one billion, three hundred seventy-nine million, eight hundred three thousand, seven hundred ninety-eight".