66506505656573 has 2 divisors, whose sum is σ = 66506505656574. Its totient is φ = 66506505656572.

The previous prime is 66506505656543. The next prime is 66506505656599. The reversal of 66506505656573 is 37565650560566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65687086029049 + 819419627524 = 8104757^2 + 905218^2 .

It is a cyclic number.

It is not a de Polignac number, because 66506505656573 - 2⁶ = 66506505656509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66506505656543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33253252828286 + 33253252828287.

It is an arithmetic number, because the mean of its divisors is an integer number (33253252828287).

Almost surely, 2^{66506505656573} is an apocalyptic number.

It is an amenable number.

66506505656573 is a deficient number, since it is larger than the sum of its proper divisors (1).

66506505656573 is an equidigital number, since it uses as much as digits as its factorization.

66506505656573 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 510300000, while the sum is 65.

The spelling of 66506505656573 in words is "sixty-six trillion, five hundred six billion, five hundred five million, six hundred fifty-six thousand, five hundred seventy-three".