81817071 has 16 divisors (see below), whose sum is σ = 124800000. Its totient is φ = 46705248.

The previous prime is 81817069. The next prime is 81817081. The reversal of 81817071 is 17071818.

It is not a de Polignac number, because 81817071 - 2¹ = 81817069 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81817031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39930 + ... + 41928.

It is an arithmetic number, because the mean of its divisors is an integer number (7800000).

Almost surely, 2^81817071 is an apocalyptic number.

81817071 is a deficient number, since it is larger than the sum of its proper divisors (42982929).

81817071 is a wasteful number, since it uses less digits than its factorization.

81817071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3958.

The product of its (nonzero) digits is 3136, while the sum is 33.

The square root of 81817071 is about 9045.2789343392. The cubic root of 81817071 is about 434.1248463977.

Adding to 81817071 its reverse (17071818), we get a palindrome (98888889).

The spelling of 81817071 in words is "eighty-one million, eight hundred seventeen thousand, seventy-one".