2100809 has 8 divisors (see below), whose sum is σ = 2239488. Its totient is φ = 1963840.

The previous prime is 2100803. The next prime is 2100821. The reversal of 2100809 is 9080012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2100809 - 2⁴ = 2100793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2100803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2924 + ... + 3570.

It is an arithmetic number, because the mean of its divisors is an integer number (279936).

2^2100809 is an apocalyptic number.

It is an amenable number.

2100809 is a deficient number, since it is larger than the sum of its proper divisors (138679).

2100809 is a wasteful number, since it uses less digits than its factorization.

2100809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 855.

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

The square root of 2100809 is about 1449.4167792599. The cubic root of 2100809 is about 128.0743586502.

The spelling of 2100809 in words is "two million, one hundred thousand, eight hundred nine".