66439705 has 4 divisors (see below), whose sum is σ = 79727652. Its totient is φ = 53151760.

The previous prime is 66439699. The next prime is 66439733. The reversal of 66439705 is 50793466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50793466 = 2 ⋅25396733.

It can be written as a sum of positive squares in 2 ways, for example, as 13601344 + 52838361 = 3688^2 + 7269^2 .

It is not a de Polignac number, because 66439705 - 2³ = 66439697 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6643966 + ... + 6643975.

It is an arithmetic number, because the mean of its divisors is an integer number (19931913).

Almost surely, 2^66439705 is an apocalyptic number.

It is an amenable number.

66439705 is a deficient number, since it is larger than the sum of its proper divisors (13287947).

66439705 is a wasteful number, since it uses less digits than its factorization.

66439705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13287946.

The product of its (nonzero) digits is 136080, while the sum is 40.

The square root of 66439705 is about 8151.0554531300. The cubic root of 66439705 is about 405.0194676412.

The spelling of 66439705 in words is "sixty-six million, four hundred thirty-nine thousand, seven hundred five".