261085831 has 2 divisors, whose sum is σ = 261085832. Its totient is φ = 261085830.

The previous prime is 261085829. The next prime is 261085871. The reversal of 261085831 is 138580162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261085831 - 2¹ = 261085829 is a prime.

It is a super-2 number, since 2×261085831² = 136331622297921122, which contains 22 as substring.

Together with 261085829, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261085871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130542915 + 130542916.

It is an arithmetic number, because the mean of its divisors is an integer number (130542916).

Almost surely, 2^261085831 is an apocalyptic number.

261085831 is a deficient number, since it is larger than the sum of its proper divisors (1).

261085831 is an equidigital number, since it uses as much as digits as its factorization.

261085831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 34.

The square root of 261085831 is about 16158.1506058088. The cubic root of 261085831 is about 639.1376985667.

The spelling of 261085831 in words is "two hundred sixty-one million, eighty-five thousand, eight hundred thirty-one".