66639699 has 32 divisors (see below), whose sum is σ = 113978880. Its totient is φ = 37692000.

The previous prime is 66639667. The next prime is 66639751. The reversal of 66639699 is 99693666.

It is not a de Polignac number, because 66639699 - 2⁵ = 66639667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66639299) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17344 + ... + 20834.

It is an arithmetic number, because the mean of its divisors is an integer number (3561840).

Almost surely, 2^66639699 is an apocalyptic number.

66639699 is a deficient number, since it is larger than the sum of its proper divisors (47339181).

66639699 is a wasteful number, since it uses less digits than its factorization.

66639699 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3608 (or 3602 counting only the distinct ones).

The product of its digits is 2834352, while the sum is 54.

The square root of 66639699 is about 8163.3142166647. The cubic root of 66639699 is about 405.4254513990.

The spelling of 66639699 in words is "sixty-six million, six hundred thirty-nine thousand, six hundred ninety-nine".