66542945264639 has 2 divisors, whose sum is σ = 66542945264640. Its totient is φ = 66542945264638.

The previous prime is 66542945264591. The next prime is 66542945264693. The reversal of 66542945264639 is 93646254924566.

Together with next prime (66542945264693) 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 66542945264639 - 2⁴⁰ = 65443433636863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66542945264839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33271472632319 + 33271472632320.

It is an arithmetic number, because the mean of its divisors is an integer number (33271472632320).

Almost surely, 2^{66542945264639} is an apocalyptic number.

66542945264639 is a deficient number, since it is larger than the sum of its proper divisors (1).

66542945264639 is an equidigital number, since it uses as much as digits as its factorization.

66542945264639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2015539200, while the sum is 71.

The spelling of 66542945264639 in words is "sixty-six trillion, five hundred forty-two billion, nine hundred forty-five million, two hundred sixty-four thousand, six hundred thirty-nine".