16518607647481 has 27 divisors (see below), whose sum is σ = 18521077973391. Its totient is φ = 14727495121344.

The previous prime is 16518607647449. The next prime is 16518607647527. The reversal of 16518607647481 is 18474670681561.

The square root of 16518607647481 is 4064309.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 12860507684025 + 3658099963456 = 3586155^2 + 1912616^2 .

It is not a de Polignac number, because 16518607647481 - 2⁵ = 16518607647449 is a prime.

It is a super-2 number, since 2×16518607647481² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16518607647881) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1312765516 + ... + 1312778098.

Almost surely, 2^{16518607647481} is an apocalyptic number.

16518607647481 is the 4064309-th square number.

16518607647481 is the 2032155-th centered octagonal number.

It is an amenable number.

16518607647481 is a deficient number, since it is larger than the sum of its proper divisors (2002470325910).

16518607647481 is an frugal number, since it uses more digits than its factorization.

16518607647481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25238 (or 12619 counting only the distinct ones).

The product of its (nonzero) digits is 54190080, while the sum is 64.

The spelling of 16518607647481 in words is "sixteen trillion, five hundred eighteen billion, six hundred seven million, six hundred forty-seven thousand, four hundred eighty-one".