261994865 has 16 divisors (see below), whose sum is σ = 343624896. Its totient is φ = 190180800.

The previous prime is 261994861. The next prime is 261994867. The reversal of 261994865 is 568499162.

It is not a de Polignac number, because 261994865 - 2² = 261994861 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261994861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26735 + ... + 35195.

It is an arithmetic number, because the mean of its divisors is an integer number (21476556).

Almost surely, 2^261994865 is an apocalyptic number.

It is an amenable number.

261994865 is a deficient number, since it is larger than the sum of its proper divisors (81630031).

261994865 is a wasteful number, since it uses less digits than its factorization.

261994865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9040.

The product of its digits is 933120, while the sum is 50.

The square root of 261994865 is about 16186.2554347817. The cubic root of 261994865 is about 639.8786106037.

The spelling of 261994865 in words is "two hundred sixty-one million, nine hundred ninety-four thousand, eight hundred sixty-five".