172161921 has 8 divisors (see below), whose sum is σ = 229733280. Its totient is φ = 114682592.

The previous prime is 172161919. The next prime is 172161931. The reversal of 172161921 is 129161271.

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 172161921 - 2¹ = 172161919 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (172161931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18516 + ... + 26213.

It is an arithmetic number, because the mean of its divisors is an integer number (28716660).

Almost surely, 2^172161921 is an apocalyptic number.

It is an amenable number.

172161921 is a deficient number, since it is larger than the sum of its proper divisors (57571359).

172161921 is a wasteful number, since it uses less digits than its factorization.

172161921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46015.

The product of its digits is 1512, while the sum is 30.

The square root of 172161921 is about 13121.0487766794. The cubic root of 172161921 is about 556.3042356577.

The spelling of 172161921 in words is "one hundred seventy-two million, one hundred sixty-one thousand, nine hundred twenty-one".