261442543 has 4 divisors (see below), whose sum is σ = 262564848. Its totient is φ = 260320240.

The previous prime is 261442477. The next prime is 261442549. The reversal of 261442543 is 345244162.

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

It is a cyclic number.

It is not a de Polignac number, because 261442543 - 2²¹ = 259345391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261442549) 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 3 ways as a sum of consecutive naturals, for example, 560803 + ... + 561268.

It is an arithmetic number, because the mean of its divisors is an integer number (65641212).

Almost surely, 2^261442543 is an apocalyptic number.

261442543 is a deficient number, since it is larger than the sum of its proper divisors (1122305).

261442543 is a wasteful number, since it uses less digits than its factorization.

261442543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1122304.

The product of its digits is 23040, while the sum is 31.

The square root of 261442543 is about 16169.1849825525. The cubic root of 261442543 is about 639.4286429074.

The spelling of 261442543 in words is "two hundred sixty-one million, four hundred forty-two thousand, five hundred forty-three".