2561509 has 8 divisors (see below), whose sum is σ = 2744280. Its totient is φ = 2382336.

The previous prime is 2561491. The next prime is 2561513. The reversal of 2561509 is 9051652.

It can be written as a sum of positive squares in 4 ways, for example, as 245025 + 2316484 = 495^2 + 1522^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2561509 - 2⁹ = 2560997 is a prime.

It is a super-2 number, since 2×2561509² = 13122656714162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561549) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 667 + ... + 2359.

It is an arithmetic number, because the mean of its divisors is an integer number (343035).

2^2561509 is an apocalyptic number.

It is an amenable number.

2561509 is a deficient number, since it is larger than the sum of its proper divisors (182771).

2561509 is a wasteful number, since it uses less digits than its factorization.

2561509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1799.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 2561509 is about 1600.4714930295. The cubic root of 2561509 is about 136.8249491390.

The spelling of 2561509 in words is "two million, five hundred sixty-one thousand, five hundred nine".