66903217921 has 4 divisors (see below), whose sum is σ = 66904240644. Its totient is φ = 66902195200.

The previous prime is 66903217883. The next prime is 66903217937. The reversal of 66903217921 is 12971230966.

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 44000935696 + 22902282225 = 209764^2 + 151335^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66903217921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66903217991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 406000 + ... + 546481.

It is an arithmetic number, because the mean of its divisors is an integer number (16726060161).

Almost surely, 2^66903217921 is an apocalyptic number.

It is an amenable number.

66903217921 is a deficient number, since it is larger than the sum of its proper divisors (1022723).

66903217921 is an equidigital number, since it uses as much as digits as its factorization.

66903217921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022722.

The product of its (nonzero) digits is 244944, while the sum is 46.

The spelling of 66903217921 in words is "sixty-six billion, nine hundred three million, two hundred seventeen thousand, nine hundred twenty-one".