261820271 has 2 divisors, whose sum is σ = 261820272. Its totient is φ = 261820270.

The previous prime is 261820193. The next prime is 261820283. The reversal of 261820271 is 172028162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261820271 - 2¹⁰ = 261819247 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261820291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130910135 + 130910136.

It is an arithmetic number, because the mean of its divisors is an integer number (130910136).

Almost surely, 2^261820271 is an apocalyptic number.

261820271 is a deficient number, since it is larger than the sum of its proper divisors (1).

261820271 is an equidigital number, since it uses as much as digits as its factorization.

261820271 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 261820271 is about 16180.8612564350. The cubic root of 261820271 is about 639.7364401431.

The spelling of 261820271 in words is "two hundred sixty-one million, eight hundred twenty thousand, two hundred seventy-one".