66517215091 has 2 divisors, whose sum is σ = 66517215092. Its totient is φ = 66517215090.

The previous prime is 66517215077. The next prime is 66517215109. The reversal of 66517215091 is 19051271566.

Together with next prime (66517215109) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66517215091 - 2⁷ = 66517214963 is a prime.

It is not a weakly prime, because it can be changed into another prime (66517215031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33258607545 + 33258607546.

It is an arithmetic number, because the mean of its divisors is an integer number (33258607546).

Almost surely, 2^66517215091 is an apocalyptic number.

66517215091 is a deficient number, since it is larger than the sum of its proper divisors (1).

66517215091 is an equidigital number, since it uses as much as digits as its factorization.

66517215091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 113400, while the sum is 43.

The spelling of 66517215091 in words is "sixty-six billion, five hundred seventeen million, two hundred fifteen thousand, ninety-one".