261968557 has 8 divisors (see below), whose sum is σ = 268906680. Its totient is φ = 255056640.

The previous prime is 261968491. The next prime is 261968573. The reversal of 261968557 is 755869162.

It can be written as a sum of positive squares in 4 ways, for example, as 94887081 + 167081476 = 9741^2 + 12926^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261968557 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261968557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261960557) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 14593 + ... + 27145.

It is an arithmetic number, because the mean of its divisors is an integer number (33613335).

Almost surely, 2^261968557 is an apocalyptic number.

It is an amenable number.

261968557 is a deficient number, since it is larger than the sum of its proper divisors (6938123).

261968557 is a wasteful number, since it uses less digits than its factorization.

261968557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13103.

The product of its digits is 907200, while the sum is 49.

The square root of 261968557 is about 16185.4427495821. The cubic root of 261968557 is about 639.8571922578.

The spelling of 261968557 in words is "two hundred sixty-one million, nine hundred sixty-eight thousand, five hundred fifty-seven".