81223171 has 4 divisors (see below), whose sum is σ = 84024000. Its totient is φ = 78422344.

The previous prime is 81223169. The next prime is 81223183. The reversal of 81223171 is 17132218.

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: 17132218 = 2 ⋅8566109.

It is a cyclic number.

It is not a de Polignac number, because 81223171 - 2¹ = 81223169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81223141) 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, 1400371 + ... + 1400428.

It is an arithmetic number, because the mean of its divisors is an integer number (21006000).

Almost surely, 2^81223171 is an apocalyptic number.

81223171 is a deficient number, since it is larger than the sum of its proper divisors (2800829).

81223171 is a wasteful number, since it uses less digits than its factorization.

81223171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2800828.

The product of its digits is 672, while the sum is 25.

The square root of 81223171 is about 9012.3898606308. The cubic root of 81223171 is about 433.0718749526.

Adding to 81223171 its reverse (17132218), we get a palindrome (98355389).

The spelling of 81223171 in words is "eighty-one million, two hundred twenty-three thousand, one hundred seventy-one".