66679999 has 4 divisors (see below), whose sum is σ = 66890664. Its totient is φ = 66469336.

The previous prime is 66679993. The next prime is 66680011. The reversal of 66679999 is 99997666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66679999 - 2¹⁷ = 66548927 is a prime.

It is a Duffinian number.

66679999 is a modest number, since divided by 9999 gives 6667 as remainder.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66679993) 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 in 3 ways as a sum of consecutive naturals, for example, 104857 + ... + 105490.

It is an arithmetic number, because the mean of its divisors is an integer number (16722666).

Almost surely, 2^66679999 is an apocalyptic number.

66679999 is a deficient number, since it is larger than the sum of its proper divisors (210665).

66679999 is a wasteful number, since it uses less digits than its factorization.

66679999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210664.

The product of its digits is 9920232, while the sum is 61.

The square root of 66679999 is about 8165.7822038063. The cubic root of 66679999 is about 405.5071612180.

The spelling of 66679999 in words is "sixty-six million, six hundred seventy-nine thousand, nine hundred ninety-nine".