261521361 has 12 divisors (see below), whose sum is σ = 379101060. Its totient is φ = 173725440.

The previous prime is 261521357. The next prime is 261521389. The reversal of 261521361 is 163125162.

It can be written as a sum of positive squares in 2 ways, for example, as 149817600 + 111703761 = 12240^2 + 10569^2 .

It is not a de Polignac number, because 261521361 - 2² = 261521357 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261521341) 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, 49176 + ... + 54233.

It is an arithmetic number, because the mean of its divisors is an integer number (31591755).

Almost surely, 2^261521361 is an apocalyptic number.

It is an amenable number.

261521361 is a deficient number, since it is larger than the sum of its proper divisors (117579699).

261521361 is a wasteful number, since it uses less digits than its factorization.

261521361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103696 (or 103693 counting only the distinct ones).

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

The square root of 261521361 is about 16171.6220893267. The cubic root of 261521361 is about 639.4928933828.

The spelling of 261521361 in words is "two hundred sixty-one million, five hundred twenty-one thousand, three hundred sixty-one".