66206921357 has 4 divisors (see below), whose sum is σ = 66889467036. Its totient is φ = 65524375680.

The previous prime is 66206921353. The next prime is 66206921369. The reversal of 66206921357 is 75312960266.

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 21546129796 + 44660791561 = 146786^2 + 211331^2 .

It is a cyclic number.

It is not a de Polignac number, because 66206921357 - 2² = 66206921353 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66206921353) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 341272694 + ... + 341272887.

It is an arithmetic number, because the mean of its divisors is an integer number (16722366759).

Almost surely, 2^66206921357 is an apocalyptic number.

It is an amenable number.

66206921357 is a deficient number, since it is larger than the sum of its proper divisors (682545679).

66206921357 is an equidigital number, since it uses as much as digits as its factorization.

66206921357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 682545678.

The product of its (nonzero) digits is 816480, while the sum is 47.

The spelling of 66206921357 in words is "sixty-six billion, two hundred six million, nine hundred twenty-one thousand, three hundred fifty-seven".