82171891 has 2 divisors, whose sum is σ = 82171892. Its totient is φ = 82171890.

The previous prime is 82171871. The next prime is 82171937. The reversal of 82171891 is 19817128.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 82171891 - 2⁷ = 82171763 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 82171891.

It is not a weakly prime, because it can be changed into another prime (82171811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41085945 + 41085946.

It is an arithmetic number, because the mean of its divisors is an integer number (41085946).

Almost surely, 2^82171891 is an apocalyptic number.

82171891 is a deficient number, since it is larger than the sum of its proper divisors (1).

82171891 is an equidigital number, since it uses as much as digits as its factorization.

82171891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 37.

The square root of 82171891 is about 9064.8712621857. The cubic root of 82171891 is about 434.7515047020.

The spelling of 82171891 in words is "eighty-two million, one hundred seventy-one thousand, eight hundred ninety-one".