81571361 has 4 divisors (see below), whose sum is σ = 82788912. Its totient is φ = 80353812.

The previous prime is 81571331. The next prime is 81571433. The reversal of 81571361 is 16317518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81571361 - 2²² = 77377057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81571331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 608675 + ... + 608808.

It is an arithmetic number, because the mean of its divisors is an integer number (20697228).

Almost surely, 2^81571361 is an apocalyptic number.

It is an amenable number.

81571361 is a deficient number, since it is larger than the sum of its proper divisors (1217551).

81571361 is a wasteful number, since it uses less digits than its factorization.

81571361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1217550.

The product of its digits is 5040, while the sum is 32.

The square root of 81571361 is about 9031.6864981021. The cubic root of 81571361 is about 433.6898280717.

Adding to 81571361 its reverse (16317518), we get a palindrome (97888879).

The spelling of 81571361 in words is "eighty-one million, five hundred seventy-one thousand, three hundred sixty-one".