261657109 has 12 divisors (see below), whose sum is σ = 304828704. Its totient is φ = 223944504.

The previous prime is 261657101. The next prime is 261657119. The reversal of 261657109 is 901756162.

It is not a de Polignac number, because 261657109 - 2³ = 261657101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261657101) 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 in 11 ways as a sum of consecutive naturals, for example, 32814 + ... + 40000.

It is an arithmetic number, because the mean of its divisors is an integer number (25402392).

Almost surely, 2^261657109 is an apocalyptic number.

It is an amenable number.

261657109 is a deficient number, since it is larger than the sum of its proper divisors (43171595).

261657109 is an equidigital number, since it uses as much as digits as its factorization.

261657109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7944 (or 7937 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 37.

The square root of 261657109 is about 16175.8186500715. The cubic root of 261657109 is about 639.6035215231.

The spelling of 261657109 in words is "two hundred sixty-one million, six hundred fifty-seven thousand, one hundred nine".