81947930247 has 24 divisors (see below), whose sum is σ = 123711664128. Its totient is φ = 52173752400.

The previous prime is 81947930203. The next prime is 81947930269. The reversal of 81947930247 is 74203974918.

It is not a de Polignac number, because 81947930247 - 2²³ = 81939541639 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81947930193 and 81947930202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81947930047) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 183079 + ... + 444312.

It is an arithmetic number, because the mean of its divisors is an integer number (5154652672).

Almost surely, 2^81947930247 is an apocalyptic number.

81947930247 is a deficient number, since it is larger than the sum of its proper divisors (41763733881).

81947930247 is a wasteful number, since it uses less digits than its factorization.

81947930247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628051 (or 628048 counting only the distinct ones).

The product of its (nonzero) digits is 3048192, while the sum is 54.

The spelling of 81947930247 in words is "eighty-one billion, nine hundred forty-seven million, nine hundred thirty thousand, two hundred forty-seven".