17929747921 has 4 divisors (see below), whose sum is σ = 17974911412. Its totient is φ = 17884584432.

The previous prime is 17929747919. The next prime is 17929747937. The reversal of 17929747921 is 12974792971.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5146053696 + 12783694225 = 71736^2 + 113065^2 .

It is a cyclic number.

It is not a de Polignac number, because 17929747921 - 2¹ = 17929747919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17929747991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22581150 + ... + 22581943.

It is an arithmetic number, because the mean of its divisors is an integer number (4493727853).

Almost surely, 2^17929747921 is an apocalyptic number.

It is an amenable number.

17929747921 is a deficient number, since it is larger than the sum of its proper divisors (45163491).

17929747921 is an equidigital number, since it uses as much as digits as its factorization.

17929747921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45163490.

The product of its digits is 4000752, while the sum is 58.

The spelling of 17929747921 in words is "seventeen billion, nine hundred twenty-nine million, seven hundred forty-seven thousand, nine hundred twenty-one".