66756321 has 24 divisors (see below), whose sum is σ = 98654400. Its totient is φ = 43487136.

The previous prime is 66756311. The next prime is 66756359. The reversal of 66756321 is 12365766.

It is not a de Polignac number, because 66756321 - 2¹⁸ = 66494177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66756311) 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 23 ways as a sum of consecutive naturals, for example, 89476 + ... + 90218.

It is an arithmetic number, because the mean of its divisors is an integer number (4110600).

Almost surely, 2^66756321 is an apocalyptic number.

It is an amenable number.

66756321 is a deficient number, since it is larger than the sum of its proper divisors (31898079).

66756321 is a wasteful number, since it uses less digits than its factorization.

66756321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 965 (or 962 counting only the distinct ones).

The product of its digits is 45360, while the sum is 36.

The square root of 66756321 is about 8170.4541489442. The cubic root of 66756321 is about 405.6618168739.

It can be divided in two parts, 6675 and 6321, that added together give a square (12996 = 114²).

The spelling of 66756321 in words is "sixty-six million, seven hundred fifty-six thousand, three hundred twenty-one".