66961665 has 24 divisors (see below), whose sum is σ = 116363520. Its totient is φ = 35621664.

The previous prime is 66961663. The next prime is 66961669. The reversal of 66961665 is 56616966.

66961665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 66961665 - 2¹ = 66961663 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 66961665.

It is not an unprimeable number, because it can be changed into a prime (66961663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18256 + ... + 21614.

It is an arithmetic number, because the mean of its divisors is an integer number (4848480).

Almost surely, 2^66961665 is an apocalyptic number.

It is an amenable number.

66961665 is a deficient number, since it is larger than the sum of its proper divisors (49401855).

66961665 is a wasteful number, since it uses less digits than its factorization.

66961665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3813 (or 3810 counting only the distinct ones).

The product of its digits is 349920, while the sum is 45.

The square root of 66961665 is about 8183.0107539951. The cubic root of 66961665 is about 406.0773328550.

The spelling of 66961665 in words is "sixty-six million, nine hundred sixty-one thousand, six hundred sixty-five".