1661517166717 has 4 divisors (see below), whose sum is σ = 1677967831836. Its totient is φ = 1645066501600.

The previous prime is 1661517166703. The next prime is 1661517166739. The reversal of 1661517166717 is 7176617151661.

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 1133062318116 + 528454848601 = 1064454^2 + 726949^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661517166717 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 (1661517160717) 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, 8225332408 + ... + 8225332609.

It is an arithmetic number, because the mean of its divisors is an integer number (419491957959).

Almost surely, 2^{1661517166717} is an apocalyptic number.

It is an amenable number.

1661517166717 is a deficient number, since it is larger than the sum of its proper divisors (16450665119).

1661517166717 is a wasteful number, since it uses less digits than its factorization.

1661517166717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16450665118.

The product of its digits is 2222640, while the sum is 55.

The spelling of 1661517166717 in words is "one trillion, six hundred sixty-one billion, five hundred seventeen million, one hundred sixty-six thousand, seven hundred seventeen".