261011961 has 12 divisors (see below), whose sum is σ = 430876992. Its totient is φ = 149149656.

The previous prime is 261011941. The next prime is 261011963. The reversal of 261011961 is 169110162.

It is not a de Polignac number, because 261011961 - 2⁹ = 261011449 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (261011963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2071461 + ... + 2071586.

It is an arithmetic number, because the mean of its divisors is an integer number (35906416).

Almost surely, 2^261011961 is an apocalyptic number.

261011961 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

261011961 is a deficient number, since it is larger than the sum of its proper divisors (169865031).

261011961 is a wasteful number, since it uses less digits than its factorization.

261011961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4143060 (or 4143057 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 261011961 is about 16155.8646008191. The cubic root of 261011961 is about 639.0774150001.

The spelling of 261011961 in words is "two hundred sixty-one million, eleven thousand, nine hundred sixty-one".