66930721 has 16 divisors (see below), whose sum is σ = 79974720. Its totient is φ = 55206720.

The previous prime is 66930719. The next prime is 66930733. The reversal of 66930721 is 12703966.

66930721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 66930721 - 2¹ = 66930719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66930821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4471 + ... + 12403.

It is an arithmetic number, because the mean of its divisors is an integer number (4998420).

Almost surely, 2^66930721 is an apocalyptic number.

It is an amenable number.

66930721 is a deficient number, since it is larger than the sum of its proper divisors (13043999).

66930721 is a wasteful number, since it uses less digits than its factorization.

66930721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8016.

The product of its (nonzero) digits is 13608, while the sum is 34.

The square root of 66930721 is about 8181.1197888798. The cubic root of 66930721 is about 406.0147717210.

The spelling of 66930721 in words is "sixty-six million, nine hundred thirty thousand, seven hundred twenty-one".