261630601 has 2 divisors, whose sum is σ = 261630602. Its totient is φ = 261630600.

The previous prime is 261630599. The next prime is 261630637. The reversal of 261630601 is 106036162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 256768576 + 4862025 = 16024^2 + 2205^2 .

It is a cyclic number.

It is not a de Polignac number, because 261630601 - 2¹ = 261630599 is a prime.

Together with 261630599, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (261630641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130815300 + 130815301.

It is an arithmetic number, because the mean of its divisors is an integer number (130815301).

Almost surely, 2^261630601 is an apocalyptic number.

It is an amenable number.

261630601 is a deficient number, since it is larger than the sum of its proper divisors (1).

261630601 is an equidigital number, since it uses as much as digits as its factorization.

261630601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 261630601 is about 16174.9992581144. Note that the first 3 decimals coincide. The cubic root of 261630601 is about 639.5819217752.

Adding to 261630601 its reverse (106036162), we get a palindrome (367666763).

The spelling of 261630601 in words is "two hundred sixty-one million, six hundred thirty thousand, six hundred one".