100820809 has 2 divisors, whose sum is σ = 100820810. Its totient is φ = 100820808.

The previous prime is 100820807. The next prime is 100820933. The reversal of 100820809 is 908028001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81504784 + 19316025 = 9028^2 + 4395^2 .

It is a cyclic number.

It is not a de Polignac number, because 100820809 - 2¹ = 100820807 is a prime.

Together with 100820807, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (100820803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50410404 + 50410405.

It is an arithmetic number, because the mean of its divisors is an integer number (50410405).

Almost surely, 2^100820809 is an apocalyptic number.

It is an amenable number.

100820809 is a deficient number, since it is larger than the sum of its proper divisors (1).

100820809 is an equidigital number, since it uses as much as digits as its factorization.

100820809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 100820809 is about 10040.9565779362. The cubic root of 100820809 is about 465.4253771207.

The spelling of 100820809 in words is "one hundred million, eight hundred twenty thousand, eight hundred nine".