172155809 has 8 divisors (see below), whose sum is σ = 198166080. Its totient is φ = 146499696.

The previous prime is 172155793. The next prime is 172155811. The reversal of 172155809 is 908551271.

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

It is not a de Polignac number, because 172155809 - 2⁴ = 172155793 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (172155869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87494 + ... + 89439.

It is an arithmetic number, because the mean of its divisors is an integer number (24770760).

Almost surely, 2^172155809 is an apocalyptic number.

It is an amenable number.

172155809 is a deficient number, since it is larger than the sum of its proper divisors (26010271).

172155809 is a wasteful number, since it uses less digits than its factorization.

172155809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177079.

The product of its (nonzero) digits is 25200, while the sum is 38.

The square root of 172155809 is about 13120.8158664010. The cubic root of 172155809 is about 556.2976523752.

The spelling of 172155809 in words is "one hundred seventy-two million, one hundred fifty-five thousand, eight hundred nine".