16571956985 has 4 divisors (see below), whose sum is σ = 19886348388. Its totient is φ = 13257565584.

The previous prime is 16571956981. The next prime is 16571956991. The reversal of 16571956985 is 58965917561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12037820089 + 4534136896 = 109717^2 + 67336^2 .

It is a cyclic number.

It is not a de Polignac number, because 16571956985 - 2² = 16571956981 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16571956981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1657195694 + ... + 1657195703.

It is an arithmetic number, because the mean of its divisors is an integer number (4971587097).

Almost surely, 2^16571956985 is an apocalyptic number.

It is an amenable number.

16571956985 is a deficient number, since it is larger than the sum of its proper divisors (3314391403).

16571956985 is an equidigital number, since it uses as much as digits as its factorization.

16571956985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3314391402.

The product of its digits is 20412000, while the sum is 62.

The spelling of 16571956985 in words is "sixteen billion, five hundred seventy-one million, nine hundred fifty-six thousand, nine hundred eighty-five".