66776665 has 8 divisors (see below), whose sum is σ = 80179848. Its totient is φ = 53389440.

The previous prime is 66776623. The next prime is 66776669. The reversal of 66776665 is 56667766.

It can be written as a sum of positive squares in 4 ways, for example, as 582169 + 66194496 = 763^2 + 8136^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66776665 - 2⁷ = 66776537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66776669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9175 + ... + 14755.

It is an arithmetic number, because the mean of its divisors is an integer number (10022481).

Almost surely, 2^66776665 is an apocalyptic number.

It is an amenable number.

66776665 is a deficient number, since it is larger than the sum of its proper divisors (13403183).

66776665 is a wasteful number, since it uses less digits than its factorization.

66776665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7979.

The product of its digits is 1905120, while the sum is 49.

The square root of 66776665 is about 8171.6990277420. The cubic root of 66776665 is about 405.7030211907.

The spelling of 66776665 in words is "sixty-six million, seven hundred seventy-six thousand, six hundred sixty-five".