261771841 has 2 divisors, whose sum is σ = 261771842. Its totient is φ = 261771840.

The previous prime is 261771833. The next prime is 261771857. The reversal of 261771841 is 148177162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138650625 + 123121216 = 11775^2 + 11096^2 .

It is a cyclic number.

It is not a de Polignac number, because 261771841 - 2³ = 261771833 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261771841.

It is not a weakly prime, because it can be changed into another prime (261771241) 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, 130885920 + 130885921.

It is an arithmetic number, because the mean of its divisors is an integer number (130885921).

Almost surely, 2^261771841 is an apocalyptic number.

It is an amenable number.

261771841 is a deficient number, since it is larger than the sum of its proper divisors (1).

261771841 is an equidigital number, since it uses as much as digits as its factorization.

261771841 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18816, while the sum is 37.

The square root of 261771841 is about 16179.3646661419. The cubic root of 261771841 is about 639.6969927947.

The spelling of 261771841 in words is "two hundred sixty-one million, seven hundred seventy-one thousand, eight hundred forty-one".