81942571 has 2 divisors, whose sum is σ = 81942572. Its totient is φ = 81942570.

The previous prime is 81942569. The next prime is 81942607. The reversal of 81942571 is 17524918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81942571 - 2¹ = 81942569 is a prime.

Together with 81942569, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81942571.

It is not a weakly prime, because it can be changed into another prime (81942521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40971285 + 40971286.

It is an arithmetic number, because the mean of its divisors is an integer number (40971286).

Almost surely, 2^81942571 is an apocalyptic number.

81942571 is a deficient number, since it is larger than the sum of its proper divisors (1).

81942571 is an equidigital number, since it uses as much as digits as its factorization.

81942571 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 37.

The square root of 81942571 is about 9052.2135966845. The cubic root of 81942571 is about 434.3467024403.

The spelling of 81942571 in words is "eighty-one million, nine hundred forty-two thousand, five hundred seventy-one".