81659671 has 2 divisors, whose sum is σ = 81659672. Its totient is φ = 81659670.

The previous prime is 81659597. The next prime is 81659689. The reversal of 81659671 is 17695618.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81659671 - 2¹¹ = 81657623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81659371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40829835 + 40829836.

It is an arithmetic number, because the mean of its divisors is an integer number (40829836).

Almost surely, 2^81659671 is an apocalyptic number.

81659671 is a deficient number, since it is larger than the sum of its proper divisors (1).

81659671 is an equidigital number, since it uses as much as digits as its factorization.

81659671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 43.

The square root of 81659671 is about 9036.5740742828. The cubic root of 81659671 is about 433.8462773268.

The spelling of 81659671 in words is "eighty-one million, six hundred fifty-nine thousand, six hundred seventy-one".