81717211 has 4 divisors (see below), whose sum is σ = 81975312. Its totient is φ = 81459112.

The previous prime is 81717203. The next prime is 81717217. The reversal of 81717211 is 11271718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81717211 - 2³ = 81717203 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81717211.

It is not an unprimeable number, because it can be changed into a prime (81717217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128575 + ... + 129208.

It is an arithmetic number, because the mean of its divisors is an integer number (20493828).

Almost surely, 2^81717211 is an apocalyptic number.

81717211 is a deficient number, since it is larger than the sum of its proper divisors (258101).

81717211 is a wasteful number, since it uses less digits than its factorization.

81717211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258100.

The product of its digits is 784, while the sum is 28.

The square root of 81717211 is about 9039.7572423157. The cubic root of 81717211 is about 433.9481540281.

Adding to 81717211 its reverse (11271718), we get a palindrome (92988929).

The spelling of 81717211 in words is "eighty-one million, seven hundred seventeen thousand, two hundred eleven".