66999998 has 16 divisors (see below), whose sum is σ = 108444336. Its totient is φ = 30862080.

The previous prime is 66999997. The next prime is 67000019. The reversal of 66999998 is 89999966.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66999997) 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 7 ways as a sum of consecutive naturals, for example, 12590 + ... + 17102.

It is an arithmetic number, because the mean of its divisors is an integer number (6777771).

Almost surely, 2^66999998 is an apocalyptic number.

66999998 is a deficient number, since it is larger than the sum of its proper divisors (41444338).

66999998 is a wasteful number, since it uses less digits than its factorization.

66999998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5099.

The product of its digits is 17006112, while the sum is 65.

The square root of 66999998 is about 8185.3526497030. The cubic root of 66999998 is about 406.1548060032.

The spelling of 66999998 in words is "sixty-six million, nine hundred ninety-nine thousand, nine hundred ninety-eight".