2506561 has 2 divisors, whose sum is σ = 2506562. Its totient is φ = 2506560.

The previous prime is 2506549. The next prime is 2506571. The reversal of 2506561 is 1656052.

2506561 = 1119² + 1120².

2506561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1254400 + 1252161 = 1120^2 + 1119^2 .

It is a cyclic number.

It is not a de Polignac number, because 2506561 - 2¹³ = 2498369 is a prime.

It is not a weakly prime, because it can be changed into another prime (2506501) 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, 1253280 + 1253281.

It is an arithmetic number, because the mean of its divisors is an integer number (1253281).

2^2506561 is an apocalyptic number.

2506561 is the 1120-th centered square number.

It is an amenable number.

2506561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2506561 is an equidigital number, since it uses as much as digits as its factorization.

2506561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 2506561 is about 1583.2122409835. The cubic root of 2506561 is about 135.8395057437.

The spelling of 2506561 in words is "two million, five hundred six thousand, five hundred sixty-one".