81332161 has 2 divisors, whose sum is σ = 81332162. Its totient is φ = 81332160.

The previous prime is 81332143. The next prime is 81332177. The reversal of 81332161 is 16123318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71503936 + 9828225 = 8456^2 + 3135^2 .

It is a cyclic number.

It is not a de Polignac number, because 81332161 - 2⁵ = 81332129 is a prime.

It is a super-2 number, since 2×81332161² = 13229840825859842, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81332101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40666080 + 40666081.

It is an arithmetic number, because the mean of its divisors is an integer number (40666081).

Almost surely, 2^81332161 is an apocalyptic number.

It is an amenable number.

81332161 is a deficient number, since it is larger than the sum of its proper divisors (1).

81332161 is an equidigital number, since it uses as much as digits as its factorization.

81332161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 25.

The square root of 81332161 is about 9018.4345093813. The cubic root of 81332161 is about 433.2654954292.

Adding to 81332161 its reverse (16123318), we get a palindrome (97455479).

The spelling of 81332161 in words is "eighty-one million, three hundred thirty-two thousand, one hundred sixty-one".