81338161 has 2 divisors, whose sum is σ = 81338162. Its totient is φ = 81338160.

The previous prime is 81338129. The next prime is 81338171. The reversal of 81338161 is 16183318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56776225 + 24561936 = 7535^2 + 4956^2 .

It is a cyclic number.

It is not a de Polignac number, because 81338161 - 2⁵ = 81338129 is a prime.

It is not a weakly prime, because it can be changed into another prime (81338111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40669080 + 40669081.

It is an arithmetic number, because the mean of its divisors is an integer number (40669081).

Almost surely, 2^81338161 is an apocalyptic number.

It is an amenable number.

81338161 is a deficient number, since it is larger than the sum of its proper divisors (1).

81338161 is an equidigital number, since it uses as much as digits as its factorization.

81338161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 31.

The square root of 81338161 is about 9018.7671552158. The cubic root of 81338161 is about 433.2761493904.

The spelling of 81338161 in words is "eighty-one million, three hundred thirty-eight thousand, one hundred sixty-one".