172120161 has 4 divisors (see below), whose sum is σ = 229493552. Its totient is φ = 114746772.

The previous prime is 172120159. The next prime is 172120177. The reversal of 172120161 is 161021271.

It is a happy number.

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 not a de Polignac number, because 172120161 - 2¹ = 172120159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (172120111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28686691 + ... + 28686696.

It is an arithmetic number, because the mean of its divisors is an integer number (57373388).

Almost surely, 2^172120161 is an apocalyptic number.

It is an amenable number.

172120161 is a deficient number, since it is larger than the sum of its proper divisors (57373391).

172120161 is an equidigital number, since it uses as much as digits as its factorization.

172120161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57373390.

The product of its (nonzero) digits is 168, while the sum is 21.

The square root of 172120161 is about 13119.4573439605. The cubic root of 172120161 is about 556.2592525330.

The spelling of 172120161 in words is "one hundred seventy-two million, one hundred twenty thousand, one hundred sixty-one".