66530839391 has 4 divisors (see below), whose sum is σ = 66539934384. Its totient is φ = 66521744400.

The previous prime is 66530839381. The next prime is 66530839429. The reversal of 66530839391 is 19393803566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66530839391 - 2¹⁸ = 66530577247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66530839321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4536515 + ... + 4551156.

It is an arithmetic number, because the mean of its divisors is an integer number (16634983596).

Almost surely, 2^66530839391 is an apocalyptic number.

66530839391 is a deficient number, since it is larger than the sum of its proper divisors (9094993).

66530839391 is an equidigital number, since it uses as much as digits as its factorization.

66530839391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9094992.

The product of its (nonzero) digits is 3149280, while the sum is 53.

The spelling of 66530839391 in words is "sixty-six billion, five hundred thirty million, eight hundred thirty-nine thousand, three hundred ninety-one".