81161771 has 4 divisors (see below), whose sum is σ = 81501600. Its totient is φ = 80821944.

The previous prime is 81161767. The next prime is 81161797. The reversal of 81161771 is 17716118.

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 81161771 - 2² = 81161767 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81161741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169556 + ... + 170033.

It is an arithmetic number, because the mean of its divisors is an integer number (20375400).

Almost surely, 2^81161771 is an apocalyptic number.

81161771 is a deficient number, since it is larger than the sum of its proper divisors (339829).

81161771 is a wasteful number, since it uses less digits than its factorization.

81161771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339828.

The product of its digits is 2352, while the sum is 32.

The square root of 81161771 is about 9008.9827949664. The cubic root of 81161771 is about 432.9627217150.

Adding to 81161771 its reverse (17716118), we get a palindrome (98877889).

The spelling of 81161771 in words is "eighty-one million, one hundred sixty-one thousand, seven hundred seventy-one".