172621217 has 2 divisors, whose sum is σ = 172621218. Its totient is φ = 172621216.

The previous prime is 172621199. The next prime is 172621219. The reversal of 172621217 is 712126271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 106832896 + 65788321 = 10336^2 + 8111^2 .

It is an emirp because it is prime and its reverse (712126271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172621217 - 2¹² = 172617121 is a prime.

It is a super-2 number, since 2×172621217² = 59596169117122178, which contains 22 as substring.

Together with 172621219, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 172621217.

It is not a weakly prime, because it can be changed into another prime (172621219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86310608 + 86310609.

It is an arithmetic number, because the mean of its divisors is an integer number (86310609).

Almost surely, 2^172621217 is an apocalyptic number.

It is an amenable number.

172621217 is a deficient number, since it is larger than the sum of its proper divisors (1).

172621217 is an equidigital number, since it uses as much as digits as its factorization.

172621217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2352, while the sum is 29.

The square root of 172621217 is about 13138.5393784850. The cubic root of 172621217 is about 556.7985018088.

Adding to 172621217 its reverse (712126271), we get a palindrome (884747488).

The spelling of 172621217 in words is "one hundred seventy-two million, six hundred twenty-one thousand, two hundred seventeen".