81171811 has 8 divisors (see below), whose sum is σ = 93004640. Its totient is φ = 69398208.

The previous prime is 81171799. The next prime is 81171823. The reversal of 81171811 is 11817118.

It is an interprime number because it is at equal distance from previous prime (81171799) and next prime (81171823).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81171811 - 2¹⁵ = 81139043 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 81171811.

It is not an unprimeable number, because it can be changed into a prime (81171851) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11826 + ... + 17383.

It is an arithmetic number, because the mean of its divisors is an integer number (11625580).

Almost surely, 2^81171811 is an apocalyptic number.

81171811 is a deficient number, since it is larger than the sum of its proper divisors (11832829).

81171811 is a wasteful number, since it uses less digits than its factorization.

81171811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29613.

The product of its digits is 448, while the sum is 28.

The square root of 81171811 is about 9009.5399993562. The cubic root of 81171811 is about 432.9805739889.

Adding to 81171811 its reverse (11817118), we get a palindrome (92988929).

The spelling of 81171811 in words is "eighty-one million, one hundred seventy-one thousand, eight hundred eleven".