261145605 has 32 divisors (see below), whose sum is σ = 489178368. Its totient is φ = 116467200.

The previous prime is 261145589. The next prime is 261145613. The reversal of 261145605 is 506541162.

It is not a de Polignac number, because 261145605 - 2⁴ = 261145589 is a prime.

It is a congruent number.

It is an unprimeable number.

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 in 31 ways as a sum of consecutive naturals, for example, 26026 + ... + 34635.

It is an arithmetic number, because the mean of its divisors is an integer number (15286824).

Almost surely, 2^261145605 is an apocalyptic number.

It is an amenable number.

261145605 is a deficient number, since it is larger than the sum of its proper divisors (228032763).

261145605 is a wasteful number, since it uses less digits than its factorization.

261145605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60717.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 261145605 is about 16160.0001547030. Note that the first 3 decimals coincide. The cubic root of 261145605 is about 639.1864703972.

Adding to 261145605 its reverse (506541162), we get a palindrome (767686767).

The spelling of 261145605 in words is "two hundred sixty-one million, one hundred forty-five thousand, six hundred five".