261025209 has 6 divisors (see below), whose sum is σ = 377036426. Its totient is φ = 174016800.

The previous prime is 261025199. The next prime is 261025223. The reversal of 261025209 is 902520162.

261025209 is a `hidden beast` number, since 2 + 610 + 25 + 20 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 243360000 + 17665209 = 15600^2 + 4203^2 .

It is not a de Polignac number, because 261025209 - 2²⁷ = 126807481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261025279) 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 5 ways as a sum of consecutive naturals, for example, 14501392 + ... + 14501409.

Almost surely, 2^261025209 is an apocalyptic number.

It is an amenable number.

261025209 is a deficient number, since it is larger than the sum of its proper divisors (116011217).

261025209 is a wasteful number, since it uses less digits than its factorization.

261025209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29002807 (or 29002804 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 261025209 is about 16156.2746015287. The cubic root of 261025209 is about 639.0882272177.

The spelling of 261025209 in words is "two hundred sixty-one million, twenty-five thousand, two hundred nine".