261329549 has 4 divisors (see below), whose sum is σ = 281431836. Its totient is φ = 241227264.

The previous prime is 261329539. The next prime is 261329569. The reversal of 261329549 is 945923162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32775625 + 228553924 = 5725^2 + 15118^2 .

It is a cyclic number.

It is not a de Polignac number, because 261329549 - 2¹² = 261325453 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261329539) 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, 10051124 + ... + 10051149.

It is an arithmetic number, because the mean of its divisors is an integer number (70357959).

Almost surely, 2^261329549 is an apocalyptic number.

It is an amenable number.

261329549 is a deficient number, since it is larger than the sum of its proper divisors (20102287).

261329549 is a wasteful number, since it uses less digits than its factorization.

261329549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20102286.

The product of its digits is 116640, while the sum is 41.

The square root of 261329549 is about 16165.6904894285. The cubic root of 261329549 is about 639.3365104760.

The spelling of 261329549 in words is "two hundred sixty-one million, three hundred twenty-nine thousand, five hundred forty-nine".