2129509 has 2 divisors, whose sum is σ = 2129510. Its totient is φ = 2129508.

The previous prime is 2129507. The next prime is 2129513. The reversal of 2129509 is 9059212.

2129509 = T₁₁₉₀ + T₁₁₉₁ + T₁₁₉₂.

2129509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1562500 + 567009 = 1250^2 + 753^2 .

It is a cyclic number.

It is not a de Polignac number, because 2129509 - 2¹ = 2129507 is a prime.

Together with 2129507, it forms a pair of twin primes.

2129509 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2129507) 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 as a sum of consecutive naturals, namely, 1064754 + 1064755.

It is an arithmetic number, because the mean of its divisors is an integer number (1064755).

2^2129509 is an apocalyptic number.

2129509 is the 1192-nd centered triangular number.

It is an amenable number.

2129509 is a deficient number, since it is larger than the sum of its proper divisors (1).

2129509 is an equidigital number, since it uses as much as digits as its factorization.

2129509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 2129509 is about 1459.2837284092. The cubic root of 2129509 is about 128.6549479097.

The spelling of 2129509 in words is "two million, one hundred twenty-nine thousand, five hundred nine".