4256561 has 2 divisors, whose sum is σ = 4256562. Its totient is φ = 4256560.

The previous prime is 4256537. The next prime is 4256563. The reversal of 4256561 is 1656524.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2890000 + 1366561 = 1700^2 + 1169^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4256561 is a prime.

Together with 4256563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (4256563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2128280 + 2128281.

It is an arithmetic number, because the mean of its divisors is an integer number (2128281).

Almost surely, 2^4256561 is an apocalyptic number.

It is an amenable number.

4256561 is a deficient number, since it is larger than the sum of its proper divisors (1).

4256561 is an equidigital number, since it uses as much as digits as its factorization.

4256561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 29.

The square root of 4256561 is about 2063.1434753793. The cubic root of 4256561 is about 162.0639005140.

The spelling of 4256561 in words is "four million, two hundred fifty-six thousand, five hundred sixty-one".