66503665 has 4 divisors (see below), whose sum is σ = 79804404. Its totient is φ = 53202928.

The previous prime is 66503659. The next prime is 66503669. The reversal of 66503665 is 56630566.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20684304 + 45819361 = 4548^2 + 6769^2 .

It is a cyclic number.

It is not a de Polignac number, because 66503665 - 2⁷ = 66503537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66503669) 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 3 ways as a sum of consecutive naturals, for example, 6650362 + ... + 6650371.

It is an arithmetic number, because the mean of its divisors is an integer number (19951101).

Almost surely, 2^66503665 is an apocalyptic number.

It is an amenable number.

66503665 is a deficient number, since it is larger than the sum of its proper divisors (13300739).

66503665 is a wasteful number, since it uses less digits than its factorization.

66503665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13300738.

The product of its (nonzero) digits is 97200, while the sum is 37.

The square root of 66503665 is about 8154.9779276219. The cubic root of 66503665 is about 405.1493936488.

The spelling of 66503665 in words is "sixty-six million, five hundred three thousand, six hundred sixty-five".