81772171 has 18 divisors (see below), whose sum is σ = 90720420. Its totient is φ = 73668816.

The previous prime is 81772169. The next prime is 81772211. The reversal of 81772171 is 17127718.

It is not a de Polignac number, because 81772171 - 2¹ = 81772169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81772571) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 588220 + ... + 588358.

Almost surely, 2^81772171 is an apocalyptic number.

81772171 is a deficient number, since it is larger than the sum of its proper divisors (8948249).

81772171 is a wasteful number, since it uses less digits than its factorization.

81772171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283 (or 211 counting only the distinct ones).

The product of its digits is 5488, while the sum is 34.

The square root of 81772171 is about 9042.7966359971. The cubic root of 81772171 is about 434.0454180986.

Adding to 81772171 its reverse (17127718), we get a palindrome (98899889).

The spelling of 81772171 in words is "eighty-one million, seven hundred seventy-two thousand, one hundred seventy-one".