2561551 has 2 divisors, whose sum is σ = 2561552. Its totient is φ = 2561550.

The previous prime is 2561549. The next prime is 2561593. The reversal of 2561551 is 1551652.

2561551 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 is a cyclic number.

It is not a de Polignac number, because 2561551 - 2¹ = 2561549 is a prime.

Together with 2561549, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2561521) 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, 1280775 + 1280776.

It is an arithmetic number, because the mean of its divisors is an integer number (1280776).

2^2561551 is an apocalyptic number.

2561551 is a deficient number, since it is larger than the sum of its proper divisors (1).

2561551 is an equidigital number, since it uses as much as digits as its factorization.

2561551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1500, while the sum is 25.

The square root of 2561551 is about 1600.4846141091. The cubic root of 2561551 is about 136.8256969556.

The spelling of 2561551 in words is "two million, five hundred sixty-one thousand, five hundred fifty-one".