261869987 has 2 divisors, whose sum is σ = 261869988. Its totient is φ = 261869986.

The previous prime is 261869963. The next prime is 261870001. The reversal of 261869987 is 789968162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261869987 - 2²⁶ = 194761123 is a prime.

It is not a weakly prime, because it can be changed into another prime (261869287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130934993 + 130934994.

It is an arithmetic number, because the mean of its divisors is an integer number (130934994).

Almost surely, 2^261869987 is an apocalyptic number.

261869987 is a deficient number, since it is larger than the sum of its proper divisors (1).

261869987 is an equidigital number, since it uses as much as digits as its factorization.

261869987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2612736, while the sum is 56.

The square root of 261869987 is about 16182.3974429007. The cubic root of 261869987 is about 639.7769299084.

The spelling of 261869987 in words is "two hundred sixty-one million, eight hundred sixty-nine thousand, nine hundred eighty-seven".