66999 has 8 divisors (see below), whose sum is σ = 93312. Its totient is φ = 42680.

The previous prime is 66977. The next prime is 67003. The reversal of 66999 is 99966.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66999 - 2¹¹ = 64951 is a prime.

66999 is a modest number, since divided by 999 gives 66 as remainder.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 66999.

It is not an unprimeable number, because it can be changed into a prime (66919) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 417 + ... + 554.

It is an arithmetic number, because the mean of its divisors is an integer number (11664).

2⁶⁶⁹⁹⁹ is an apocalyptic number.

66999 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

66999 is a deficient number, since it is larger than the sum of its proper divisors (26313).

66999 is a wasteful number, since it uses less digits than its factorization.

66999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 997.

The product of its digits is 26244, while the sum is 39.

The square root of 66999 is about 258.8416504352. The cubic root of 66999 is about 40.6152789364.

Subtracting from 66999 its product of digits (26244), we obtain a triangular number (40755 = T₂₈₅).

The spelling of 66999 in words is "sixty-six thousand, nine hundred ninety-nine".