171988981 has 2 divisors, whose sum is σ = 171988982. Its totient is φ = 171988980.

The previous prime is 171988979. The next prime is 171989011. The reversal of 171988981 is 189889171.

171988981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 144216081 + 27772900 = 12009^2 + 5270^2 .

It is a cyclic number.

It is not a de Polignac number, because 171988981 - 2¹ = 171988979 is a prime.

It is a super-2 number, since 2×171988981² = 59160419170836722, which contains 22 as substring.

Together with 171988979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (171988681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85994490 + 85994491.

It is an arithmetic number, because the mean of its divisors is an integer number (85994491).

Almost surely, 2^171988981 is an apocalyptic number.

It is an amenable number.

171988981 is a deficient number, since it is larger than the sum of its proper divisors (1).

171988981 is an equidigital number, since it uses as much as digits as its factorization.

171988981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 52.

The square root of 171988981 is about 13114.4569464389. The cubic root of 171988981 is about 556.1179004411.

The spelling of 171988981 in words is "one hundred seventy-one million, nine hundred eighty-eight thousand, nine hundred eighty-one".