171889391 has 2 divisors, whose sum is σ = 171889392. Its totient is φ = 171889390.

The previous prime is 171889381. The next prime is 171889429. The reversal of 171889391 is 193988171.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 171889391 - 2¹⁴ = 171873007 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (171889321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85944695 + 85944696.

It is an arithmetic number, because the mean of its divisors is an integer number (85944696).

Almost surely, 2^171889391 is an apocalyptic number.

171889391 is a deficient number, since it is larger than the sum of its proper divisors (1).

171889391 is an equidigital number, since it uses as much as digits as its factorization.

171889391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 47.

The square root of 171889391 is about 13110.6594418435. The cubic root of 171889391 is about 556.0105399292.

The spelling of 171889391 in words is "one hundred seventy-one million, eight hundred eighty-nine thousand, three hundred ninety-one".