171981993 has 8 divisors (see below), whose sum is σ = 229370400. Its totient is φ = 114624128.

The previous prime is 171981989. The next prime is 171982001. The reversal of 171981993 is 399189171.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 171981993 - 2² = 171981989 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (171981913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15673 + ... + 24281.

It is an arithmetic number, because the mean of its divisors is an integer number (28671300).

Almost surely, 2^171981993 is an apocalyptic number.

It is an amenable number.

171981993 is a deficient number, since it is larger than the sum of its proper divisors (57388407).

171981993 is an equidigital number, since it uses as much as digits as its factorization.

171981993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15271.

The product of its digits is 122472, while the sum is 48.

The square root of 171981993 is about 13114.1905201961. The cubic root of 171981993 is about 556.1103685545.

It can be divided in two parts, 17198 and 1993, that added together give a palindrome (19191).

The spelling of 171981993 in words is "one hundred seventy-one million, nine hundred eighty-one thousand, nine hundred ninety-three".