66717665 has 12 divisors (see below), whose sum is σ = 93132756. Its totient is φ = 45749088.

The previous prime is 66717647. The next prime is 66717727. The reversal of 66717665 is 56671766.

It can be written as a sum of positive squares in 2 ways, for example, as 35904064 + 30813601 = 5992^2 + 5551^2 .

It is not a de Polignac number, because 66717665 - 2⁶ = 66717601 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 135914 + ... + 136403.

It is an arithmetic number, because the mean of its divisors is an integer number (7761063).

Almost surely, 2^66717665 is an apocalyptic number.

It is an amenable number.

66717665 is a deficient number, since it is larger than the sum of its proper divisors (26415091).

66717665 is a wasteful number, since it uses less digits than its factorization.

66717665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272336 (or 272329 counting only the distinct ones).

The product of its digits is 317520, while the sum is 44.

The square root of 66717665 is about 8168.0882096118. The cubic root of 66717665 is about 405.5835007397.

The spelling of 66717665 in words is "sixty-six million, seven hundred seventeen thousand, six hundred sixty-five".