171990945 has 160 divisors (see below), whose sum is σ = 386580480. Its totient is φ = 71383680.

The previous prime is 171990937. The next prime is 171990947. The reversal of 171990945 is 549099171.

It is not a de Polignac number, because 171990945 - 2³ = 171990937 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 171990945.

It is not an unprimeable number, because it can be changed into a prime (171990947) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 1669764 + ... + 1669866.

It is an arithmetic number, because the mean of its divisors is an integer number (2416128).

Almost surely, 2^171990945 is an apocalyptic number.

171990945 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

171990945 is an abundant number, since it is smaller than the sum of its proper divisors (214589535).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

171990945 is a wasteful number, since it uses less digits than its factorization.

171990945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177 (or 168 counting only the distinct ones).

The product of its (nonzero) digits is 102060, while the sum is 45.

The square root of 171990945 is about 13114.5318254218. The cubic root of 171990945 is about 556.1200172655.

The spelling of 171990945 in words is "one hundred seventy-one million, nine hundred ninety thousand, nine hundred forty-five".