261641205 has 32 divisors (see below), whose sum is σ = 531590400. Its totient is φ = 119606976.

The previous prime is 261641179. The next prime is 261641249. The reversal of 261641205 is 502146162.

261641205 is a `hidden beast` number, since 2 + 616 + 41 + 2 + 0 + 5 = 666.

It is not a de Polignac number, because 261641205 - 2¹⁶ = 261575669 is a prime.

It is a super-2 number, since 2×261641205² = 136912240307704050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 137490 + ... + 139379.

It is an arithmetic number, because the mean of its divisors is an integer number (16612200).

Almost surely, 2^261641205 is an apocalyptic number.

It is an amenable number.

261641205 is an abundant number, since it is smaller than the sum of its proper divisors (269949195).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261641205 is a wasteful number, since it uses less digits than its factorization.

261641205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276890 (or 276884 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 261641205 is about 16175.3270446072. The cubic root of 261641205 is about 639.5905625013.

Adding to 261641205 its reverse (502146162), we get a palindrome (763787367).

The spelling of 261641205 in words is "two hundred sixty-one million, six hundred forty-one thousand, two hundred five".