261636587 has 2 divisors, whose sum is σ = 261636588. Its totient is φ = 261636586.

The previous prime is 261636563. The next prime is 261636601. The reversal of 261636587 is 785636162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261636587 - 2²⁰ = 260588011 is a prime.

It is not a weakly prime, because it can be changed into another prime (261636547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130818293 + 130818294.

It is an arithmetic number, because the mean of its divisors is an integer number (130818294).

Almost surely, 2^261636587 is an apocalyptic number.

261636587 is a deficient number, since it is larger than the sum of its proper divisors (1).

261636587 is an equidigital number, since it uses as much as digits as its factorization.

261636587 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 44.

The square root of 261636587 is about 16175.1842957043. The cubic root of 261636587 is about 639.5867995280.

The spelling of 261636587 in words is "two hundred sixty-one million, six hundred thirty-six thousand, five hundred eighty-seven".