561551643 has 8 divisors (see below), whose sum is σ = 831928400. Its totient is φ = 374367744.

The previous prime is 561551611. The next prime is 561551657. The reversal of 561551643 is 346155165.

561551643 is a `hidden beast` number, since 5 + 6 + 1 + 5 + 5 + 1 + 643 = 666.

It is not a de Polignac number, because 561551643 - 2⁵ = 561551611 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 561551598 and 561551607.

It is not an unprimeable number, because it can be changed into a prime (561551603) 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, 10399078 + ... + 10399131.

It is an arithmetic number, because the mean of its divisors is an integer number (103991050).

Almost surely, 2^561551643 is an apocalyptic number.

561551643 is a deficient number, since it is larger than the sum of its proper divisors (270376757).

561551643 is a wasteful number, since it uses less digits than its factorization.

561551643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20798218 (or 20798212 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The square root of 561551643 is about 23697.0808961779. The cubic root of 561551643 is about 825.0176392923.

The spelling of 561551643 in words is "five hundred sixty-one million, five hundred fifty-one thousand, six hundred forty-three".