261539324857 has 2 divisors, whose sum is σ = 261539324858. Its totient is φ = 261539324856.

The previous prime is 261539324801. The next prime is 261539324863. The reversal of 261539324857 is 758423935162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 217809823401 + 43729501456 = 466701^2 + 209116^2 .

It is a cyclic number.

It is not a de Polignac number, because 261539324857 - 2¹¹ = 261539322809 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261539324798 and 261539324807.

It is not a weakly prime, because it can be changed into another prime (261539324897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130769662428 + 130769662429.

It is an arithmetic number, because the mean of its divisors is an integer number (130769662429).

Almost surely, 2^261539324857 is an apocalyptic number.

It is an amenable number.

261539324857 is a deficient number, since it is larger than the sum of its proper divisors (1).

261539324857 is an equidigital number, since it uses as much as digits as its factorization.

261539324857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10886400, while the sum is 55.

The spelling of 261539324857 in words is "two hundred sixty-one billion, five hundred thirty-nine million, three hundred twenty-four thousand, eight hundred fifty-seven".