66542643 has 18 divisors (see below), whose sum is σ = 97767852. Its totient is φ = 43612560.

The previous prime is 66542633. The next prime is 66542683. The reversal of 66542643 is 34624566.

66542643 is a `hidden beast` number, since 6 + 6 + 5 + 4 + 2 + 643 = 666.

It is not a de Polignac number, because 66542643 - 2¹⁸ = 66280499 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66542598 and 66542607.

It is not an unprimeable number, because it can be changed into a prime (66542603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 32496 + ... + 34482.

Almost surely, 2^66542643 is an apocalyptic number.

66542643 is a deficient number, since it is larger than the sum of its proper divisors (31225209).

66542643 is a wasteful number, since it uses less digits than its factorization.

66542643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2115 (or 2051 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The square root of 66542643 is about 8157.3674062163. The cubic root of 66542643 is about 405.2285312865.

The spelling of 66542643 in words is "sixty-six million, five hundred forty-two thousand, six hundred forty-three".