261891248555 has 8 divisors (see below), whose sum is σ = 314279132544. Its totient is φ = 209506576000.

The previous prime is 261891248527. The next prime is 261891248557. The reversal of 261891248555 is 555842198162.

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

It is not a de Polignac number, because 261891248555 - 2²⁶ = 261824139691 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 261891248555.

It is not an unprimeable number, because it can be changed into a prime (261891248557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 619646 + ... + 952755.

It is an arithmetic number, because the mean of its divisors is an integer number (39284891568).

Almost surely, 2^261891248555 is an apocalyptic number.

261891248555 is a deficient number, since it is larger than the sum of its proper divisors (52387883989).

261891248555 is a wasteful number, since it uses less digits than its factorization.

261891248555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605717.

The product of its digits is 6912000, while the sum is 56.

The spelling of 261891248555 in words is "two hundred sixty-one billion, eight hundred ninety-one million, two hundred forty-eight thousand, five hundred fifty-five".