81947347 has 4 divisors (see below), whose sum is σ = 81966600. Its totient is φ = 81928096.

The previous prime is 81947329. The next prime is 81947351. The reversal of 81947347 is 74374918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74374918 = 2 ⋅37187459.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81947347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81947357) 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, 97 + ... + 12802.

It is an arithmetic number, because the mean of its divisors is an integer number (20491650).

Almost surely, 2^81947347 is an apocalyptic number.

81947347 is a deficient number, since it is larger than the sum of its proper divisors (19253).

81947347 is a wasteful number, since it uses less digits than its factorization.

81947347 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19252.

The product of its digits is 169344, while the sum is 43.

The square root of 81947347 is about 9052.4773957188. The cubic root of 81947347 is about 434.3551408687.

The spelling of 81947347 in words is "eighty-one million, nine hundred forty-seven thousand, three hundred forty-seven".