17661603172171 has 4 divisors (see below), whose sum is σ = 20184689339632. Its totient is φ = 15138517004712.

The previous prime is 17661603172121. The next prime is 17661603172181. The reversal of 17661603172171 is 17127130616671.

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

It is a cyclic number.

It is not a de Polignac number, because 17661603172171 - 2¹⁵ = 17661603139403 is a prime.

It is a super-2 number, since 2×17661603172171² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (17661603172111) 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, 1261543083720 + ... + 1261543083733.

It is an arithmetic number, because the mean of its divisors is an integer number (5046172334908).

Almost surely, 2^{17661603172171} is an apocalyptic number.

17661603172171 is a deficient number, since it is larger than the sum of its proper divisors (2523086167461).

17661603172171 is an equidigital number, since it uses as much as digits as its factorization.

17661603172171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2523086167460.

The product of its (nonzero) digits is 444528, while the sum is 49.

The spelling of 17661603172171 in words is "seventeen trillion, six hundred sixty-one billion, six hundred three million, one hundred seventy-two thousand, one hundred seventy-one".