82171009 has 2 divisors, whose sum is σ = 82171010. Its totient is φ = 82171008.

The previous prime is 82170989. The next prime is 82171027. The reversal of 82171009 is 90017128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62457409 + 19713600 = 7903^2 + 4440^2 .

It is a cyclic number.

It is not a de Polignac number, because 82171009 - 2¹⁵ = 82138241 is a prime.

It is not a weakly prime, because it can be changed into another prime (82171039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41085504 + 41085505.

It is an arithmetic number, because the mean of its divisors is an integer number (41085505).

Almost surely, 2^82171009 is an apocalyptic number.

It is an amenable number.

82171009 is a deficient number, since it is larger than the sum of its proper divisors (1).

82171009 is an equidigital number, since it uses as much as digits as its factorization.

82171009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 82171009 is about 9064.8226127156. The cubic root of 82171009 is about 434.7499492139.

The spelling of 82171009 in words is "eighty-two million, one hundred seventy-one thousand, nine".