261855011 has 12 divisors (see below), whose sum is σ = 289913400. Its totient is φ = 236322240.

The previous prime is 261854969. The next prime is 261855019. The reversal of 261855011 is 110558162.

It is not a de Polignac number, because 261855011 - 2⁶ = 261854947 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261855019) 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 11 ways as a sum of consecutive naturals, for example, 9035 + ... + 24603.

It is an arithmetic number, because the mean of its divisors is an integer number (24159450).

Almost surely, 2^261855011 is an apocalyptic number.

261855011 is a deficient number, since it is larger than the sum of its proper divisors (28058389).

261855011 is a wasteful number, since it uses less digits than its factorization.

261855011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15730 (or 15719 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 29.

The square root of 261855011 is about 16181.9347112760. The cubic root of 261855011 is about 639.7647336756.

The spelling of 261855011 in words is "two hundred sixty-one million, eight hundred fifty-five thousand, eleven".