66678999 has 16 divisors (see below), whose sum is σ = 94193280. Its totient is φ = 41839200.

The previous prime is 66678979. The next prime is 66679009. The reversal of 66678999 is 99987666.

It is a happy number.

It is not a de Polignac number, because 66678999 - 2⁵ = 66678967 is a prime.

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 (66678949) 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 15 ways as a sum of consecutive naturals, for example, 5224 + ... + 12674.

It is an arithmetic number, because the mean of its divisors is an integer number (5887080).

Almost surely, 2^66678999 is an apocalyptic number.

66678999 is a deficient number, since it is larger than the sum of its proper divisors (27514281).

66678999 is a wasteful number, since it uses less digits than its factorization.

66678999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7630.

The product of its digits is 8817984, while the sum is 60.

The square root of 66678999 is about 8165.7209724555. The cubic root of 66678999 is about 405.5051340775.

The spelling of 66678999 in words is "sixty-six million, six hundred seventy-eight thousand, nine hundred ninety-nine".