66821305 has 16 divisors (see below), whose sum is σ = 85100544. Its totient is φ = 50195200.

The previous prime is 66821303. The next prime is 66821317. The reversal of 66821305 is 50312866.

It is not a de Polignac number, because 66821305 - 2¹ = 66821303 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66821303) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57480 + ... + 58630.

It is an arithmetic number, because the mean of its divisors is an integer number (5318784).

Almost surely, 2^66821305 is an apocalyptic number.

It is an amenable number.

66821305 is a deficient number, since it is larger than the sum of its proper divisors (18279239).

66821305 is a wasteful number, since it uses less digits than its factorization.

66821305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1856.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 66821305 is about 8174.4299495439. The cubic root of 66821305 is about 405.7934048037.

The spelling of 66821305 in words is "sixty-six million, eight hundred twenty-one thousand, three hundred five".