2139209 has 4 divisors (see below), whose sum is σ = 2174340. Its totient is φ = 2104080.

The previous prime is 2139199. The next prime is 2139211. The reversal of 2139209 is 9029312.

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 1149184 + 990025 = 1072^2 + 995^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2139209 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2139409) 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, 17474 + ... + 17595.

It is an arithmetic number, because the mean of its divisors is an integer number (543585).

2^2139209 is an apocalyptic number.

It is an amenable number.

2139209 is a deficient number, since it is larger than the sum of its proper divisors (35131).

2139209 is an equidigital number, since it uses as much as digits as its factorization.

2139209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35130.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 2139209 is about 1462.6035006112. The cubic root of 2139209 is about 128.8499948978.

The spelling of 2139209 in words is "two million, one hundred thirty-nine thousand, two hundred nine".