261685507 has 2 divisors, whose sum is σ = 261685508. Its totient is φ = 261685506.

The previous prime is 261685483. The next prime is 261685517. The reversal of 261685507 is 705586162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261685507 - 2²³ = 253296899 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261685507.

It is not a weakly prime, because it can be changed into another prime (261685517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130842753 + 130842754.

It is an arithmetic number, because the mean of its divisors is an integer number (130842754).

Almost surely, 2^261685507 is an apocalyptic number.

261685507 is a deficient number, since it is larger than the sum of its proper divisors (1).

261685507 is an equidigital number, since it uses as much as digits as its factorization.

261685507 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 261685507 is about 16176.6964179959. The cubic root of 261685507 is about 639.6266596978.

The spelling of 261685507 in words is "two hundred sixty-one million, six hundred eighty-five thousand, five hundred seven".