181396217 has 4 divisors (see below), whose sum is σ = 181674660. Its totient is φ = 181117776.

The previous prime is 181396213. The next prime is 181396223. The reversal of 181396217 is 712693181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 712693181 = 709 ⋅1005209.

It can be written as a sum of positive squares in 2 ways, for example, as 90079081 + 91317136 = 9491^2 + 9556^2 .

It is a cyclic number.

It is not a de Polignac number, because 181396217 - 2² = 181396213 is a prime.

It is a super-2 number, since 2×181396217² = 65809175083822178, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181396213) 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, 138242 + ... + 139547.

It is an arithmetic number, because the mean of its divisors is an integer number (45418665).

Almost surely, 2^181396217 is an apocalyptic number.

It is an amenable number.

181396217 is a deficient number, since it is larger than the sum of its proper divisors (278443).

181396217 is an equidigital number, since it uses as much as digits as its factorization.

181396217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278442.

The product of its digits is 18144, while the sum is 38.

The square root of 181396217 is about 13468.3412861421. The cubic root of 181396217 is about 566.0777372032.

The spelling of 181396217 in words is "one hundred eighty-one million, three hundred ninety-six thousand, two hundred seventeen".