171985987 has 2 divisors, whose sum is σ = 171985988. Its totient is φ = 171985986.

The previous prime is 171985943. The next prime is 171985997. The reversal of 171985987 is 789589171.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 171985987 - 2¹⁵ = 171953219 is a prime.

It is not a weakly prime, because it can be changed into another prime (171985937) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85992993 + 85992994.

It is an arithmetic number, because the mean of its divisors is an integer number (85992994).

Almost surely, 2^171985987 is an apocalyptic number.

171985987 is a deficient number, since it is larger than the sum of its proper divisors (1).

171985987 is an equidigital number, since it uses as much as digits as its factorization.

171985987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1270080, while the sum is 55.

The square root of 171985987 is about 13114.3427971058. The cubic root of 171985987 is about 556.1146734385.

The spelling of 171985987 in words is "one hundred seventy-one million, nine hundred eighty-five thousand, nine hundred eighty-seven".