17981016521 has 16 divisors (see below), whose sum is σ = 20857912320. Its totient is φ = 15364071360.

The previous prime is 17981016497. The next prime is 17981016541. The reversal of 17981016521 is 12561018971.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 17981016521 - 2¹⁰ = 17981015497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17981016541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 960686 + ... + 979223.

It is an arithmetic number, because the mean of its divisors is an integer number (1303619520).

Almost surely, 2^17981016521 is an apocalyptic number.

It is an amenable number.

17981016521 is a deficient number, since it is larger than the sum of its proper divisors (2876895799).

17981016521 is a wasteful number, since it uses less digits than its factorization.

17981016521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1939976.

The product of its (nonzero) digits is 30240, while the sum is 41.

The spelling of 17981016521 in words is "seventeen billion, nine hundred eighty-one million, sixteen thousand, five hundred twenty-one".