16521665517 has 96 divisors (see below), whose sum is σ = 29213184000. Its totient is φ = 8788590720.

The previous prime is 16521665473. The next prime is 16521665527. The reversal of 16521665517 is 71556612561.

It is a happy number.

16521665517 is a `hidden beast` number, since 1 + 6 + 521 + 66 + 55 + 17 = 666.

It is not a de Polignac number, because 16521665517 - 2¹⁰ = 16521664493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16521665527) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 18135292 + ... + 18136202.

It is an arithmetic number, because the mean of its divisors is an integer number (304304000).

Almost surely, 2^16521665517 is an apocalyptic number.

It is an amenable number.

16521665517 is a deficient number, since it is larger than the sum of its proper divisors (12691518483).

16521665517 is a wasteful number, since it uses less digits than its factorization.

16521665517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1191 (or 1188 counting only the distinct ones).

The product of its digits is 378000, while the sum is 45.

The spelling of 16521665517 in words is "sixteen billion, five hundred twenty-one million, six hundred sixty-five thousand, five hundred seventeen".