66819664 has 10 divisors (see below), whose sum is σ = 129463130. Its totient is φ = 33409824.

The previous prime is 66819661. The next prime is 66819667. The reversal of 66819664 is 46691866.

It is an interprime number because it is at equal distance from previous prime (66819661) and next prime (66819667).

It can be written as a sum of positive squares in only one way, i.e., 36481600 + 30338064 = 6040^2 + 5508^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66819661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2088099 + ... + 2088130.

It is an arithmetic number, because the mean of its divisors is an integer number (12946313).

Almost surely, 2^66819664 is an apocalyptic number.

It is an amenable number.

66819664 is a deficient number, since it is larger than the sum of its proper divisors (62643466).

66819664 is a wasteful number, since it uses less digits than its factorization.

66819664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4176237 (or 4176231 counting only the distinct ones).

The product of its digits is 373248, while the sum is 46.

The square root of 66819664 is about 8174.3295749560. The cubic root of 66819664 is about 405.7900829468.

The spelling of 66819664 in words is "sixty-six million, eight hundred nineteen thousand, six hundred sixty-four".