81508161 has 8 divisors (see below), whose sum is σ = 124202944. Its totient is φ = 46576080.

The previous prime is 81508127. The next prime is 81508181. The reversal of 81508161 is 16180518.

It is a happy number.

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

It is not a de Polignac number, because 81508161 - 2¹⁰ = 81507137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81508121) 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, 1940650 + ... + 1940691.

It is an arithmetic number, because the mean of its divisors is an integer number (15525368).

Almost surely, 2^81508161 is an apocalyptic number.

It is an amenable number.

81508161 is a deficient number, since it is larger than the sum of its proper divisors (42694783).

81508161 is a wasteful number, since it uses less digits than its factorization.

81508161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3881351.

The product of its (nonzero) digits is 1920, while the sum is 30.

The square root of 81508161 is about 9028.1870273051. The cubic root of 81508161 is about 433.5777941480.

Adding to 81508161 its reverse (16180518), we get a palindrome (97688679).

The spelling of 81508161 in words is "eighty-one million, five hundred eight thousand, one hundred sixty-one".