66666799 has 4 divisors (see below), whose sum is σ = 67605840. Its totient is φ = 65727760.

The previous prime is 66666793. The next prime is 66666827. The reversal of 66666799 is 99766666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99766666 = 2 ⋅49883333.

It is a cyclic number.

It is not a de Polignac number, because 66666799 - 2¹¹ = 66664751 is a prime.

It is a Duffinian number.

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 (66666793) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 469414 + ... + 469555.

It is an arithmetic number, because the mean of its divisors is an integer number (16901460).

Almost surely, 2^66666799 is an apocalyptic number.

66666799 is a deficient number, since it is larger than the sum of its proper divisors (939041).

66666799 is an equidigital number, since it uses as much as digits as its factorization.

66666799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 939040.

The product of its digits is 4408992, while the sum is 55.

The square root of 66666799 is about 8164.9739130018. The cubic root of 66666799 is about 405.4804013307.

The spelling of 66666799 in words is "sixty-six million, six hundred sixty-six thousand, seven hundred ninety-nine".