66564728355841 has 9 divisors (see below), whose sum is σ = 69584874389121. Its totient is φ = 63670430239812.

The previous prime is 66564728355817. The next prime is 66564728355869. The reversal of 66564728355841 is 14855382746566.

The square root of 66564728355841 is 8158721.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 66564728355841 - 2⁹ = 66564728355329 is a prime.

It is a super-2 number, since 2×66564728355841² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66564728358841) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 187473220 + ... + 187827946.

Almost surely, 2^{66564728355841} is an apocalyptic number.

66564728355841 is the 8158721-st square number.

66564728355841 is the 4079361-st centered octagonal number.

It is an amenable number.

66564728355841 is a deficient number, since it is larger than the sum of its proper divisors (3020146033280).

66564728355841 is an frugal number, since it uses more digits than its factorization.

66564728355841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 709500 (or 354750 counting only the distinct ones).

The product of its digits is 1161216000, while the sum is 70.

The spelling of 66564728355841 in words is "sixty-six trillion, five hundred sixty-four billion, seven hundred twenty-eight million, three hundred fifty-five thousand, eight hundred forty-one".