261388849 has 2 divisors, whose sum is σ = 261388850. Its totient is φ = 261388848.

The previous prime is 261388847. The next prime is 261388877. The reversal of 261388849 is 948883162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 260499600 + 889249 = 16140^2 + 943^2 .

It is a cyclic number.

It is not a de Polignac number, because 261388849 - 2¹ = 261388847 is a prime.

Together with 261388847, 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 (261388847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130694424 + 130694425.

It is an arithmetic number, because the mean of its divisors is an integer number (130694425).

Almost surely, 2^261388849 is an apocalyptic number.

It is an amenable number.

261388849 is a deficient number, since it is larger than the sum of its proper divisors (1).

261388849 is an equidigital number, since it uses as much as digits as its factorization.

261388849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 663552, while the sum is 49.

The square root of 261388849 is about 16167.5245167589. The cubic root of 261388849 is about 639.3848654973.

The spelling of 261388849 in words is "two hundred sixty-one million, three hundred eighty-eight thousand, eight hundred forty-nine".