66611999 has 4 divisors (see below), whose sum is σ = 66642336. Its totient is φ = 66581664.

The previous prime is 66611977. The next prime is 66612011. The reversal of 66611999 is 99911666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99911666 = 2 ⋅49955833.

It is a cyclic number.

It is not a de Polignac number, because 66611999 - 2¹⁶ = 66546463 is a prime.

66611999 is a strobogrammatic number because it is the same when read upside-down.

It is a Duffinian number.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66611959) 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 3 ways as a sum of consecutive naturals, for example, 11594 + ... + 16359.

It is an arithmetic number, because the mean of its divisors is an integer number (16660584).

Almost surely, 2^66611999 is an apocalyptic number.

66611999 is a deficient number, since it is larger than the sum of its proper divisors (30337).

66611999 is a wasteful number, since it uses less digits than its factorization.

66611999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30336.

The product of its digits is 157464, while the sum is 47.

The square root of 66611999 is about 8161.6174254862. The cubic root of 66611999 is about 405.3692694657.

The spelling of 66611999 in words is "sixty-six million, six hundred eleven thousand, nine hundred ninety-nine".