81660871 has 2 divisors, whose sum is σ = 81660872. Its totient is φ = 81660870.

The previous prime is 81660857. The next prime is 81660893. The reversal of 81660871 is 17806618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81660871 - 2⁷ = 81660743 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81660871.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81660811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40830435 + 40830436.

It is an arithmetic number, because the mean of its divisors is an integer number (40830436).

Almost surely, 2^81660871 is an apocalyptic number.

81660871 is a deficient number, since it is larger than the sum of its proper divisors (1).

81660871 is an equidigital number, since it uses as much as digits as its factorization.

81660871 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 81660871 is about 9036.6404708830. The cubic root of 81660871 is about 433.8484024598.

The spelling of 81660871 in words is "eighty-one million, six hundred sixty thousand, eight hundred seventy-one".