172081999 has 4 divisors (see below), whose sum is σ = 172128136. Its totient is φ = 172035864.

The previous prime is 172081981. The next prime is 172082003. The reversal of 172081999 is 999180271.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 999180271 = 8669 ⋅115259.

It is a cyclic number.

It is not a de Polignac number, because 172081999 - 2¹⁷ = 171950927 is a prime.

It is a super-2 number, since 2×172081999² = 59224428759672002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172081909) 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 3 ways as a sum of consecutive naturals, for example, 16929 + ... + 25114.

It is an arithmetic number, because the mean of its divisors is an integer number (43032034).

Almost surely, 2^172081999 is an apocalyptic number.

172081999 is a deficient number, since it is larger than the sum of its proper divisors (46137).

172081999 is an equidigital number, since it uses as much as digits as its factorization.

172081999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46136.

The product of its (nonzero) digits is 81648, while the sum is 46.

The square root of 172081999 is about 13118.0028586672. The cubic root of 172081999 is about 556.2181387465.

The spelling of 172081999 in words is "one hundred seventy-two million, eighty-one thousand, nine hundred ninety-nine".