261505687 has 2 divisors, whose sum is σ = 261505688. Its totient is φ = 261505686.

The previous prime is 261505681. The next prime is 261505691. The reversal of 261505687 is 786505162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261505687 - 2²³ = 253117079 is a prime.

It is equal to p_14273698 and since 261505687 and 14273698 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261505681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130752843 + 130752844.

It is an arithmetic number, because the mean of its divisors is an integer number (130752844).

Almost surely, 2^261505687 is an apocalyptic number.

261505687 is a deficient number, since it is larger than the sum of its proper divisors (1).

261505687 is an equidigital number, since it uses as much as digits as its factorization.

261505687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 100800, while the sum is 40.

The square root of 261505687 is about 16171.1374677232. The cubic root of 261505687 is about 639.4801173558.

The spelling of 261505687 in words is "two hundred sixty-one million, five hundred five thousand, six hundred eighty-seven".