171988993 has 4 divisors (see below), whose sum is σ = 187624368. Its totient is φ = 156353620.

The previous prime is 171988981. The next prime is 171989011. The reversal of 171988993 is 399889171.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 171988993 - 2¹⁷ = 171857921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (171988903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7817671 + ... + 7817692.

It is an arithmetic number, because the mean of its divisors is an integer number (46906092).

Almost surely, 2^171988993 is an apocalyptic number.

It is an amenable number.

171988993 is a deficient number, since it is larger than the sum of its proper divisors (15635375).

171988993 is a wasteful number, since it uses less digits than its factorization.

171988993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15635374.

The product of its digits is 979776, while the sum is 55.

The square root of 171988993 is about 13114.4574039493. The cubic root of 171988993 is about 556.1179133749.

The spelling of 171988993 in words is "one hundred seventy-one million, nine hundred eighty-eight thousand, nine hundred ninety-three".