81781313959 has 8 divisors (see below), whose sum is σ = 86594477760. Its totient is φ = 76968427776.

The previous prime is 81781313947. The next prime is 81781313963. The reversal of 81781313959 is 95931318718.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81781313959 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 (81781313359) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1105362 + ... + 1177024.

It is an arithmetic number, because the mean of its divisors is an integer number (10824309720).

Almost surely, 2^81781313959 is an apocalyptic number.

81781313959 is a deficient number, since it is larger than the sum of its proper divisors (4813163801).

81781313959 is a wasteful number, since it uses less digits than its factorization.

81781313959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138809.

The product of its digits is 1632960, while the sum is 55.

The spelling of 81781313959 in words is "eighty-one billion, seven hundred eighty-one million, three hundred thirteen thousand, nine hundred fifty-nine".