81831670639 has 2 divisors, whose sum is σ = 81831670640. Its totient is φ = 81831670638.

The previous prime is 81831670637. The next prime is 81831670727. The reversal of 81831670639 is 93607613818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81831670639 - 2¹ = 81831670637 is a prime.

Together with 81831670637, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81831670633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40915835319 + 40915835320.

It is an arithmetic number, because the mean of its divisors is an integer number (40915835320).

Almost surely, 2^81831670639 is an apocalyptic number.

81831670639 is a deficient number, since it is larger than the sum of its proper divisors (1).

81831670639 is an equidigital number, since it uses as much as digits as its factorization.

81831670639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1306368, while the sum is 52.

The spelling of 81831670639 in words is "eighty-one billion, eight hundred thirty-one million, six hundred seventy thousand, six hundred thirty-nine".