66806257 has 6 divisors (see below), whose sum is σ = 77713458. Its totient is φ = 57262464.

The previous prime is 66806251. The next prime is 66806263. The reversal of 66806257 is 75260866.

It is an interprime number because it is at equal distance from previous prime (66806251) and next prime (66806263).

It can be written as a sum of positive squares in only one way, i.e., 46294416 + 20511841 = 6804^2 + 4529^2 .

It is not a de Polignac number, because 66806257 - 2²³ = 58417649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66806251) 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 5 ways as a sum of consecutive naturals, for example, 681648 + ... + 681745.

It is an arithmetic number, because the mean of its divisors is an integer number (12952243).

Almost surely, 2^66806257 is an apocalyptic number.

It is an amenable number.

66806257 is a deficient number, since it is larger than the sum of its proper divisors (10907201).

66806257 is a wasteful number, since it uses less digits than its factorization.

66806257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1363407 (or 1363400 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 40.

The square root of 66806257 is about 8173.5094665633. The cubic root of 66806257 is about 405.7629412781.

The spelling of 66806257 in words is "sixty-six million, eight hundred six thousand, two hundred fifty-seven".