66644971 has 2 divisors, whose sum is σ = 66644972. Its totient is φ = 66644970.

The previous prime is 66644959. The next prime is 66644999. The reversal of 66644971 is 17944666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66644971 - 2¹⁷ = 66513899 is a prime.

It is not a weakly prime, because it can be changed into another prime (60644971) 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, 33322485 + 33322486.

It is an arithmetic number, because the mean of its divisors is an integer number (33322486).

Almost surely, 2^66644971 is an apocalyptic number.

66644971 is a deficient number, since it is larger than the sum of its proper divisors (1).

66644971 is an equidigital number, since it uses as much as digits as its factorization.

66644971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 43.

The square root of 66644971 is about 8163.6371183438. The cubic root of 66644971 is about 405.4361424568.

The spelling of 66644971 in words is "sixty-six million, six hundred forty-four thousand, nine hundred seventy-one".