66549947 has 2 divisors, whose sum is σ = 66549948. Its totient is φ = 66549946.

The previous prime is 66549943. The next prime is 66549991. The reversal of 66549947 is 74994566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66549947 - 2² = 66549943 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 66549895 and 66549904.

It is not a weakly prime, because it can be changed into another prime (66549941) 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, 33274973 + 33274974.

It is an arithmetic number, because the mean of its divisors is an integer number (33274974).

Almost surely, 2^66549947 is an apocalyptic number.

66549947 is a deficient number, since it is larger than the sum of its proper divisors (1).

66549947 is an equidigital number, since it uses as much as digits as its factorization.

66549947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1632960, while the sum is 50.

The square root of 66549947 is about 8157.8150873871. The cubic root of 66549947 is about 405.2433572726.

The spelling of 66549947 in words is "sixty-six million, five hundred forty-nine thousand, nine hundred forty-seven".