81428071 has 2 divisors, whose sum is σ = 81428072. Its totient is φ = 81428070.

The previous prime is 81428057. The next prime is 81428077. The reversal of 81428071 is 17082418.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81428071 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81428077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40714035 + 40714036.

It is an arithmetic number, because the mean of its divisors is an integer number (40714036).

Almost surely, 2^81428071 is an apocalyptic number.

81428071 is a deficient number, since it is larger than the sum of its proper divisors (1).

81428071 is an equidigital number, since it uses as much as digits as its factorization.

81428071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 81428071 is about 9023.7503844023. The cubic root of 81428071 is about 433.4357362853.

The spelling of 81428071 in words is "eighty-one million, four hundred twenty-eight thousand, seventy-one".