261821100344563 has 16 divisors (see below), whose sum is σ = 277263182246976. Its totient is φ = 246383559152640.

The previous prime is 261821100344533. The next prime is 261821100344581. The reversal of 261821100344563 is 365443001128162.

It is a cyclic number.

It is not a de Polignac number, because 261821100344563 - 2⁹ = 261821100344051 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261821100344513) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5242373370 + ... + 5242423312.

It is an arithmetic number, because the mean of its divisors is an integer number (17328948890436).

Almost surely, 2^{261821100344563} is an apocalyptic number.

261821100344563 is a deficient number, since it is larger than the sum of its proper divisors (15442081902413).

261821100344563 is a wasteful number, since it uses less digits than its factorization.

261821100344563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89214.

The product of its (nonzero) digits is 829440, while the sum is 46.

The spelling of 261821100344563 in words is "two hundred sixty-one trillion, eight hundred twenty-one billion, one hundred million, three hundred forty-four thousand, five hundred sixty-three".