2101009 has 4 divisors (see below), whose sum is σ = 2119716. Its totient is φ = 2082304.

The previous prime is 2101007. The next prime is 2101019. The reversal of 2101009 is 9001012.

2101009 = T₁₁₈₂ + T₁₁₈₃ + T₁₁₈₄.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 483025 + 1617984 = 695^2 + 1272^2 .

It is a cyclic number.

It is not a de Polignac number, because 2101009 - 2¹ = 2101007 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2101009.

It is not an unprimeable number, because it can be changed into a prime (2101003) 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 3 ways as a sum of consecutive naturals, for example, 9184 + ... + 9409.

It is an arithmetic number, because the mean of its divisors is an integer number (529929).

2^2101009 is an apocalyptic number.

2101009 is the 1184-th centered triangular number.

It is an amenable number.

2101009 is a deficient number, since it is larger than the sum of its proper divisors (18707).

2101009 is a wasteful number, since it uses less digits than its factorization.

2101009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18706.

The product of its (nonzero) digits is 18, while the sum is 13.

The square root of 2101009 is about 1449.4857708857. The cubic root of 2101009 is about 128.0784228081.

The spelling of 2101009 in words is "two million, one hundred one thousand, nine".