261630641 has 2 divisors, whose sum is σ = 261630642. Its totient is φ = 261630640.

The previous prime is 261630637. The next prime is 261630653. The reversal of 261630641 is 146036162.

It is a happy number.

261630641 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 can be written as a sum of positive squares in only one way, i.e., 261630625 + 16 = 16175^2 + 4^2 .

It is a cyclic number.

It is not a de Polignac number, because 261630641 - 2² = 261630637 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (261630601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130815320 + 130815321.

It is an arithmetic number, because the mean of its divisors is an integer number (130815321).

Almost surely, 2^261630641 is an apocalyptic number.

It is an amenable number.

261630641 is a deficient number, since it is larger than the sum of its proper divisors (1).

261630641 is an equidigital number, since it uses as much as digits as its factorization.

261630641 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 261630641 is about 16175.0004945904. Note that the first 3 decimals coincide. The cubic root of 261630641 is about 639.5819543699.

The spelling of 261630641 in words is "two hundred sixty-one million, six hundred thirty thousand, six hundred forty-one".