66542191 has 2 divisors, whose sum is σ = 66542192. Its totient is φ = 66542190.

The previous prime is 66542143. The next prime is 66542251. The reversal of 66542191 is 19124566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66542191 - 2⁹ = 66541679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66542101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33271095 + 33271096.

It is an arithmetic number, because the mean of its divisors is an integer number (33271096).

Almost surely, 2^66542191 is an apocalyptic number.

66542191 is a deficient number, since it is larger than the sum of its proper divisors (1).

66542191 is an equidigital number, since it uses as much as digits as its factorization.

66542191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 34.

The square root of 66542191 is about 8157.3397011526. The cubic root of 66542191 is about 405.2276137610.

The spelling of 66542191 in words is "sixty-six million, five hundred forty-two thousand, one hundred ninety-one".