66839999 has 16 divisors (see below), whose sum is σ = 70625280. Its totient is φ = 63180000.

The previous prime is 66839987. The next prime is 66840029. The reversal of 66839999 is 99993866.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 66839999 - 2¹² = 66835903 is a prime.

It is a Duffinian number.

66839999 is a modest number, since divided by 9999 gives 6683 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66839959) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 442574 + ... + 442724.

It is an arithmetic number, because the mean of its divisors is an integer number (4414080).

Almost surely, 2^66839999 is an apocalyptic number.

66839999 is a deficient number, since it is larger than the sum of its proper divisors (3785281).

66839999 is a wasteful number, since it uses less digits than its factorization.

66839999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422.

The product of its digits is 5668704, while the sum is 59.

The square root of 66839999 is about 8175.5733132301. The cubic root of 66839999 is about 405.8312430082.

The spelling of 66839999 in words is "sixty-six million, eight hundred thirty-nine thousand, nine hundred ninety-nine".