2509656561 has 16 divisors (see below), whose sum is σ = 3768944320. Its totient is φ = 1650183840.

The previous prime is 2509656551. The next prime is 2509656581. The reversal of 2509656561 is 1656569052.

2509656561 is a `hidden beast` number, since 25 + 0 + 9 + 6 + 565 + 61 = 666.

2509656561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2509656561 - 2⁵ = 2509656529 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2509656521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 634675 + ... + 638616.

It is an arithmetic number, because the mean of its divisors is an integer number (235559020).

Almost surely, 2^2509656561 is an apocalyptic number.

It is an amenable number.

2509656561 is a deficient number, since it is larger than the sum of its proper divisors (1259287759).

2509656561 is a wasteful number, since it uses less digits than its factorization.

2509656561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1273373 (or 1273367 counting only the distinct ones).

The product of its (nonzero) digits is 486000, while the sum is 45.

The square root of 2509656561 is about 50096.4725404893. The cubic root of 2509656561 is about 1358.9540258022.

The spelling of 2509656561 in words is "two billion, five hundred nine million, six hundred fifty-six thousand, five hundred sixty-one".