81017281 has 2 divisors, whose sum is σ = 81017282. Its totient is φ = 81017280.

The previous prime is 81017269. The next prime is 81017303. The reversal of 81017281 is 18271018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74666881 + 6350400 = 8641^2 + 2520^2 .

It is a cyclic number.

It is not a de Polignac number, because 81017281 - 2⁵ = 81017249 is a prime.

It is a super-2 number, since 2×81017281² = 13127599641265922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81017221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40508640 + 40508641.

It is an arithmetic number, because the mean of its divisors is an integer number (40508641).

Almost surely, 2^81017281 is an apocalyptic number.

It is an amenable number.

81017281 is a deficient number, since it is larger than the sum of its proper divisors (1).

81017281 is an equidigital number, since it uses as much as digits as its factorization.

81017281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 81017281 is about 9000.9600043551. The cubic root of 81017281 is about 432.7056386757.

Adding to 81017281 its reverse (18271018), we get a palindrome (99288299).

The spelling of 81017281 in words is "eighty-one million, seventeen thousand, two hundred eighty-one".