261425561 has 4 divisors (see below), whose sum is σ = 261505572. Its totient is φ = 261345552.

The previous prime is 261425557. The next prime is 261425587. The reversal of 261425561 is 165524162.

261425561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 243953161 + 17472400 = 15619^2 + 4180^2 .

It is a cyclic number.

It is not a de Polignac number, because 261425561 - 2² = 261425557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261425261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34886 + ... + 41711.

It is an arithmetic number, because the mean of its divisors is an integer number (65376393).

Almost surely, 2^261425561 is an apocalyptic number.

It is an amenable number.

261425561 is a deficient number, since it is larger than the sum of its proper divisors (80011).

261425561 is an equidigital number, since it uses as much as digits as its factorization.

261425561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80010.

The product of its digits is 14400, while the sum is 32.

The square root of 261425561 is about 16168.6598393311. The cubic root of 261425561 is about 639.4147979121.

The spelling of 261425561 in words is "two hundred sixty-one million, four hundred twenty-five thousand, five hundred sixty-one".