261779085 has 24 divisors (see below), whose sum is σ = 469399320. Its totient is φ = 134800512.

The previous prime is 261779083. The next prime is 261779099. The reversal of 261779085 is 580977162.

It can be written as a sum of positive squares in 4 ways, for example, as 92102409 + 169676676 = 9597^2 + 13026^2 .

It is not a de Polignac number, because 261779085 - 2¹ = 261779083 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 261779085.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261779083) 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 in 23 ways as a sum of consecutive naturals, for example, 98994 + ... + 101603.

It is an arithmetic number, because the mean of its divisors is an integer number (19558305).

Almost surely, 2^261779085 is an apocalyptic number.

It is an amenable number.

261779085 is a deficient number, since it is larger than the sum of its proper divisors (207620235).

261779085 is a wasteful number, since it uses less digits than its factorization.

261779085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200637 (or 200634 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The square root of 261779085 is about 16179.5885299967. The cubic root of 261779085 is about 639.7028935087.

The spelling of 261779085 in words is "two hundred sixty-one million, seven hundred seventy-nine thousand, eighty-five".