261329 has 2 divisors, whose sum is σ = 261330. Its totient is φ = 261328.

The previous prime is 261323. The next prime is 261337. The reversal of 261329 is 923162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 211600 + 49729 = 460^2 + 223^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261329 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p₂₂₉₃₇ and since 261329 and 22937 have the same sum of digits, it is a Honaker prime.

It is a nialpdrome in base 8.

It is not a weakly prime, because it can be changed into another prime (261323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130664 + 130665.

It is an arithmetic number, because the mean of its divisors is an integer number (130665).

2²⁶¹³²⁹ is an apocalyptic number.

It is an amenable number.

261329 is a deficient number, since it is larger than the sum of its proper divisors (1).

261329 is an equidigital number, since it uses as much as digits as its factorization.

261329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 23.

The square root of 261329 is about 511.2034819913. The cubic root of 261329 is about 63.9336062771.

The spelling of 261329 in words is "two hundred sixty-one thousand, three hundred twenty-nine".