261006605 has 4 divisors (see below), whose sum is σ = 313207932. Its totient is φ = 208805280.

The previous prime is 261006539. The next prime is 261006611. The reversal of 261006605 is 506600162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 143544361 + 117462244 = 11981^2 + 10838^2 .

It is not a de Polignac number, because 261006605 - 2⁸ = 261006349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26100656 + ... + 26100665.

It is an arithmetic number, because the mean of its divisors is an integer number (78301983).

Almost surely, 2^261006605 is an apocalyptic number.

It is an amenable number.

261006605 is a deficient number, since it is larger than the sum of its proper divisors (52201327).

261006605 is an equidigital number, since it uses as much as digits as its factorization.

261006605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52201326.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 261006605 is about 16155.6988397284. The cubic root of 261006605 is about 639.0730436525.

Adding to 261006605 its reverse (506600162), we get a palindrome (767606767).

The spelling of 261006605 in words is "two hundred sixty-one million, six thousand, six hundred five".