261606329 has 4 divisors (see below), whose sum is σ = 262152960. Its totient is φ = 261059700.

The previous prime is 261606313. The next prime is 261606337. The reversal of 261606329 is 923606162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 923606162 = 2 ⋅461803081.

It is a cyclic number.

It is not a de Polignac number, because 261606329 - 2⁴ = 261606313 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261606379) 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 in 3 ways as a sum of consecutive naturals, for example, 272597 + ... + 273554.

It is an arithmetic number, because the mean of its divisors is an integer number (65538240).

Almost surely, 2^261606329 is an apocalyptic number.

It is an amenable number.

261606329 is a deficient number, since it is larger than the sum of its proper divisors (546631).

261606329 is an equidigital number, since it uses as much as digits as its factorization.

261606329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546630.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 261606329 is about 16174.2489470145. The cubic root of 261606329 is about 639.5621427274.

The spelling of 261606329 in words is "two hundred sixty-one million, six hundred six thousand, three hundred twenty-nine".