16721456517 has 12 divisors (see below), whose sum is σ = 24253438924. Its totient is φ = 11101380480.

The previous prime is 16721456497. The next prime is 16721456519. The reversal of 16721456517 is 71565412761.

16721456517 is a `hidden beast` number, since 1 + 6 + 72 + 1 + 4 + 565 + 17 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 5133149316 + 11588307201 = 71646^2 + 107649^2 .

It is not a de Polignac number, because 16721456517 - 2⁸ = 16721456261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16721456519) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3852478 + ... + 3856815.

Almost surely, 2^16721456517 is an apocalyptic number.

It is an amenable number.

16721456517 is a deficient number, since it is larger than the sum of its proper divisors (7531982407).

16721456517 is a wasteful number, since it uses less digits than its factorization.

16721456517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7709540 (or 7709537 counting only the distinct ones).

The product of its digits is 352800, while the sum is 45.

The spelling of 16721456517 in words is "sixteen billion, seven hundred twenty-one million, four hundred fifty-six thousand, five hundred seventeen".