81945671 has 2 divisors, whose sum is σ = 81945672. Its totient is φ = 81945670.

The previous prime is 81945649. The next prime is 81945709. The reversal of 81945671 is 17654918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81945671 - 2¹⁰ = 81944647 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81945601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40972835 + 40972836.

It is an arithmetic number, because the mean of its divisors is an integer number (40972836).

Almost surely, 2^81945671 is an apocalyptic number.

81945671 is a deficient number, since it is larger than the sum of its proper divisors (1).

81945671 is an equidigital number, since it uses as much as digits as its factorization.

81945671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 41.

The square root of 81945671 is about 9052.3848239014. The cubic root of 81945671 is about 434.3521796820.

The spelling of 81945671 in words is "eighty-one million, nine hundred forty-five thousand, six hundred seventy-one".