82100009 has 2 divisors, whose sum is σ = 82100010. Its totient is φ = 82100008.

The previous prime is 82099973. The next prime is 82100027. The reversal of 82100009 is 90000128.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61669609 + 20430400 = 7853^2 + 4520^2 .

It is a cyclic number.

It is not a de Polignac number, because 82100009 - 2¹⁶ = 82034473 is a prime.

It is a super-2 number, since 2×82100009² = 13480822955600162, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (82100609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41050004 + 41050005.

It is an arithmetic number, because the mean of its divisors is an integer number (41050005).

Almost surely, 2^82100009 is an apocalyptic number.

It is an amenable number.

82100009 is a deficient number, since it is larger than the sum of its proper divisors (1).

82100009 is an equidigital number, since it uses as much as digits as its factorization.

82100009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 82100009 is about 9060.9055286986. The cubic root of 82100009 is about 434.6246976548.

The spelling of 82100009 in words is "eighty-two million, one hundred thousand, nine".