81712071 has 40 divisors (see below), whose sum is σ = 140367744. Its totient is φ = 46403280.

The previous prime is 81712069. The next prime is 81712079. The reversal of 81712071 is 17021718.

It is not a de Polignac number, because 81712071 - 2¹ = 81712069 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81712079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 119296 + ... + 119978.

Almost surely, 2^81712071 is an apocalyptic number.

81712071 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81712071 is a deficient number, since it is larger than the sum of its proper divisors (58655673).

81712071 is a wasteful number, since it uses less digits than its factorization.

81712071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913 (or 904 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 81712071 is about 9039.4729381751. The cubic root of 81712071 is about 433.9390554133.

Adding to 81712071 its reverse (17021718), we get a palindrome (98733789).

The spelling of 81712071 in words is "eighty-one million, seven hundred twelve thousand, seventy-one".