2155709 has 4 divisors (see below), whose sum is σ = 2225280. Its totient is φ = 2086140.

The previous prime is 2155691. The next prime is 2155711. The reversal of 2155709 is 9075512.

2155709 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2155709 - 2¹⁶ = 2090173 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2155799) 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 in 3 ways as a sum of consecutive naturals, for example, 34739 + ... + 34800.

It is an arithmetic number, because the mean of its divisors is an integer number (556320).

2^2155709 is an apocalyptic number.

It is an amenable number.

2155709 is a deficient number, since it is larger than the sum of its proper divisors (69571).

2155709 is an equidigital number, since it uses as much as digits as its factorization.

2155709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69570.

The product of its (nonzero) digits is 3150, while the sum is 29.

The square root of 2155709 is about 1468.2332920895. The cubic root of 2155709 is about 129.1804257744.

The spelling of 2155709 in words is "two million, one hundred fifty-five thousand, seven hundred nine".