561728891 has 2 divisors, whose sum is σ = 561728892. Its totient is φ = 561728890.

The previous prime is 561728879. The next prime is 561728953. The reversal of 561728891 is 198827165.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561728891 is a prime.

It is not a weakly prime, because it can be changed into another prime (561728831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280864445 + 280864446.

It is an arithmetic number, because the mean of its divisors is an integer number (280864446).

Almost surely, 2^561728891 is an apocalyptic number.

561728891 is a deficient number, since it is larger than the sum of its proper divisors (1).

561728891 is an equidigital number, since it uses as much as digits as its factorization.

561728891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 47.

The square root of 561728891 is about 23700.8204710301. The cubic root of 561728891 is about 825.1044329383.

The spelling of 561728891 in words is "five hundred sixty-one million, seven hundred twenty-eight thousand, eight hundred ninety-one".