261761 has 2 divisors, whose sum is σ = 261762. Its totient is φ = 261760.

The previous prime is 261757. The next prime is 261773. The reversal of 261761 is 167162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160000 + 101761 = 400^2 + 319^2 .

It is a cyclic number.

It is not a de Polignac number, because 261761 - 2² = 261757 is a prime.

It is a super-2 number, since 2×261761² = 137037642242, which contains 22 as substring.

It is equal to p₂₂₉₇₃ and since 261761 and 22973 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130880 + 130881.

It is an arithmetic number, because the mean of its divisors is an integer number (130881).

2²⁶¹⁷⁶¹ is an apocalyptic number.

It is an amenable number.

261761 is a deficient number, since it is larger than the sum of its proper divisors (1).

261761 is an equidigital number, since it uses as much as digits as its factorization.

261761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 23.

The square root of 261761 is about 511.6258398478. The cubic root of 261761 is about 63.9688161885.

The spelling of 261761 in words is "two hundred sixty-one thousand, seven hundred sixty-one".