16851991517 has 8 divisors (see below), whose sum is σ = 17250312576. Its totient is φ = 16455327552.

The previous prime is 16851991483. The next prime is 16851991549. The reversal of 16851991517 is 71519915861.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16851991517 - 2³⁰ = 15778249693 is a prime.

It is a super-2 number, since 2×16851991517² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16851991817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 393683 + ... + 434384.

It is an arithmetic number, because the mean of its divisors is an integer number (2156289072).

Almost surely, 2^16851991517 is an apocalyptic number.

It is an amenable number.

16851991517 is a deficient number, since it is larger than the sum of its proper divisors (398321059).

16851991517 is an equidigital number, since it uses as much as digits as its factorization.

16851991517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 828547.

The product of its digits is 680400, while the sum is 53.

The spelling of 16851991517 in words is "sixteen billion, eight hundred fifty-one million, nine hundred ninety-one thousand, five hundred seventeen".