81000071 has 2 divisors, whose sum is σ = 81000072. Its totient is φ = 81000070.

The previous prime is 81000061. The next prime is 81000077. The reversal of 81000071 is 17000018.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81000071 is a prime.

It is a super-2 number, since 2×81000071² = 13122023004010082, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81000077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40500035 + 40500036.

It is an arithmetic number, because the mean of its divisors is an integer number (40500036).

Almost surely, 2^81000071 is an apocalyptic number.

81000071 is a deficient number, since it is larger than the sum of its proper divisors (1).

81000071 is an equidigital number, since it uses as much as digits as its factorization.

81000071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 56, while the sum is 17.

The square root of 81000071 is about 9000.0039444436. The cubic root of 81000071 is about 432.6749975116.

Adding to 81000071 its reverse (17000018), we get a palindrome (98000089).

The spelling of 81000071 in words is "eighty-one million, seventy-one", and thus it is an aban number and an uban number.