261656423410205 has 4 divisors (see below), whose sum is σ = 313987708092252. Its totient is φ = 209325138728160.

The previous prime is 261656423410201. The next prime is 261656423410241. The reversal of 261656423410205 is 502014324656162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 165394697984569 + 96261725425636 = 12860587^2 + 9811306^2 .

It is not a de Polignac number, because 261656423410205 - 2² = 261656423410201 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261656423410205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261656423410201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26165642341016 + ... + 26165642341025.

It is an arithmetic number, because the mean of its divisors is an integer number (78496927023063).

Almost surely, 2^{261656423410205} is an apocalyptic number.

It is an amenable number.

261656423410205 is a deficient number, since it is larger than the sum of its proper divisors (52331284682047).

261656423410205 is an equidigital number, since it uses as much as digits as its factorization.

261656423410205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52331284682046.

The product of its (nonzero) digits is 2073600, while the sum is 47.

The spelling of 261656423410205 in words is "two hundred sixty-one trillion, six hundred fifty-six billion, four hundred twenty-three million, four hundred ten thousand, two hundred five".