66408993 has 24 divisors (see below), whose sum is σ = 111270848. Its totient is φ = 37379232.

The previous prime is 66408989. The next prime is 66409003. The reversal of 66408993 is 39980466.

66408993 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 66408993 - 2² = 66408989 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66408973) 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 23 ways as a sum of consecutive naturals, for example, 3646 + ... + 12087.

Almost surely, 2^66408993 is an apocalyptic number.

66408993 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

It is an amenable number.

66408993 is a deficient number, since it is larger than the sum of its proper divisors (44861855).

66408993 is a wasteful number, since it uses less digits than its factorization.

66408993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15813 (or 15810 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The square root of 66408993 is about 8149.1713075625. The cubic root of 66408993 is about 404.9570507724.

The spelling of 66408993 in words is "sixty-six million, four hundred eight thousand, nine hundred ninety-three".