172005221 has 2 divisors, whose sum is σ = 172005222. Its totient is φ = 172005220.

The previous prime is 172005181. The next prime is 172005257. The reversal of 172005221 is 122500271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 171741025 + 264196 = 13105^2 + 514^2 .

It is an emirp because it is prime and its reverse (122500271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172005221 - 2¹⁰ = 172004197 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 172005193 and 172005202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172005521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86002610 + 86002611.

It is an arithmetic number, because the mean of its divisors is an integer number (86002611).

Almost surely, 2^172005221 is an apocalyptic number.

It is an amenable number.

172005221 is a deficient number, since it is larger than the sum of its proper divisors (1).

172005221 is an equidigital number, since it uses as much as digits as its factorization.

172005221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 172005221 is about 13115.0760958524. The cubic root of 172005221 is about 556.1354036370.

Adding to 172005221 its reverse (122500271), we get a palindrome (294505492).

The spelling of 172005221 in words is "one hundred seventy-two million, five thousand, two hundred twenty-one".