66561543 has 12 divisors (see below), whose sum is σ = 96216120. Its totient is φ = 44341296.

The previous prime is 66561527. The next prime is 66561569. The reversal of 66561543 is 34516566.

66561543 is a `hidden beast` number, since 66 + 56 + 1 + 543 = 666.

It is not a de Polignac number, because 66561543 - 2⁴ = 66561527 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66561498 and 66561507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66562543) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19180 + ... + 22382.

It is an arithmetic number, because the mean of its divisors is an integer number (8018010).

Almost surely, 2^66561543 is an apocalyptic number.

66561543 is a deficient number, since it is larger than the sum of its proper divisors (29654577).

66561543 is a wasteful number, since it uses less digits than its factorization.

66561543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5518 (or 5515 counting only the distinct ones).

The product of its digits is 64800, while the sum is 36.

The square root of 66561543 is about 8158.5257859493. The cubic root of 66561543 is about 405.2668931244.

The spelling of 66561543 in words is "sixty-six million, five hundred sixty-one thousand, five hundred forty-three".