2101809 has 16 divisors (see below), whose sum is σ = 2967552. Its totient is φ = 1320528.

The previous prime is 2101807. The next prime is 2101811. The reversal of 2101809 is 9081012.

It is an interprime number because it is at equal distance from previous prime (2101807) and next prime (2101811).

It is not a de Polignac number, because 2101809 - 2¹ = 2101807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2101807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5544 + ... + 5910.

It is an arithmetic number, because the mean of its divisors is an integer number (185472).

2^2101809 is an apocalyptic number.

It is an amenable number.

2101809 is a deficient number, since it is larger than the sum of its proper divisors (865743).

2101809 is a wasteful number, since it uses less digits than its factorization.

2101809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 476.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 2101809 is about 1449.7617045570. The cubic root of 2101809 is about 128.0946768613.

The spelling of 2101809 in words is "two million, one hundred one thousand, eight hundred nine".