81278017 has 2 divisors, whose sum is σ = 81278018. Its totient is φ = 81278016.

The previous prime is 81278009. The next prime is 81278051. The reversal of 81278017 is 71087218.

It is an a-pointer prime, because the next prime (81278051) can be obtained adding 81278017 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62346816 + 18931201 = 7896^2 + 4351^2 .

It is a cyclic number.

It is not a de Polignac number, because 81278017 - 2³ = 81278009 is a prime.

It is a super-2 number, since 2×81278017² = 13212232094904578, which contains 22 as substring.

It is equal to p_4739803 and since 81278017 and 4739803 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81275017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40639008 + 40639009.

It is an arithmetic number, because the mean of its divisors is an integer number (40639009).

Almost surely, 2^81278017 is an apocalyptic number.

It is an amenable number.

81278017 is a deficient number, since it is larger than the sum of its proper divisors (1).

81278017 is an equidigital number, since it uses as much as digits as its factorization.

81278017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 81278017 is about 9015.4321582495. The cubic root of 81278017 is about 433.1693303771.

The spelling of 81278017 in words is "eighty-one million, two hundred seventy-eight thousand, seventeen".