17721394816 has 64 divisors (see below), whose sum is σ = 35949614400. Its totient is φ = 8699146240.

The previous prime is 17721394793. The next prime is 17721394837. The reversal of 17721394816 is 61849312771.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 17721394816.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11410296 + ... + 11411848.

It is an arithmetic number, because the mean of its divisors is an integer number (561712725).

Almost surely, 2^17721394816 is an apocalyptic number.

17721394816 is a gapful number since it is divisible by the number (16) 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 17721394816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17974807200).

17721394816 is an abundant number, since it is smaller than the sum of its proper divisors (18228219584).

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

17721394816 is a wasteful number, since it uses less digits than its factorization.

17721394816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3137 (or 3125 counting only the distinct ones).

The product of its digits is 508032, while the sum is 49.

The spelling of 17721394816 in words is "seventeen billion, seven hundred twenty-one million, three hundred ninety-four thousand, eight hundred sixteen".