261565988 has 12 divisors (see below), whose sum is σ = 464188032. Its totient is φ = 128940840.

The previous prime is 261565981. The next prime is 261565991. The reversal of 261565988 is 889565162.

It is a super-2 number, since 2×261565988² = 136833532156832288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261565981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 460220 + ... + 460787.

It is an arithmetic number, because the mean of its divisors is an integer number (38682336).

Almost surely, 2^261565988 is an apocalyptic number.

It is an amenable number.

261565988 is a deficient number, since it is larger than the sum of its proper divisors (202622044).

261565988 is a wasteful number, since it uses less digits than its factorization.

261565988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 921082 (or 921080 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 50.

The square root of 261565988 is about 16173.0018240276. The cubic root of 261565988 is about 639.5292664806.

The spelling of 261565988 in words is "two hundred sixty-one million, five hundred sixty-five thousand, nine hundred eighty-eight".