81947389339 has 4 divisors (see below), whose sum is σ = 86767824024. Its totient is φ = 77126954656.

The previous prime is 81947389331. The next prime is 81947389361. The reversal of 81947389339 is 93398374918.

It is a happy number.

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 81947389339 - 2³ = 81947389331 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81947389331) 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, 2410217317 + ... + 2410217350.

It is an arithmetic number, because the mean of its divisors is an integer number (21691956006).

Almost surely, 2^81947389339 is an apocalyptic number.

81947389339 is a deficient number, since it is larger than the sum of its proper divisors (4820434685).

81947389339 is a wasteful number, since it uses less digits than its factorization.

81947389339 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4820434684.

The product of its digits is 35271936, while the sum is 64.

The spelling of 81947389339 in words is "eighty-one billion, nine hundred forty-seven million, three hundred eighty-nine thousand, three hundred thirty-nine".