81218328047 has 18 divisors (see below), whose sum is σ = 82859893704. Its totient is φ = 79608846720.

The previous prime is 81218328043. The next prime is 81218328083. The reversal of 81218328047 is 74082381218.

It is not a de Polignac number, because 81218328047 - 2² = 81218328043 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81218327989 and 81218328007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81218328043) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 161467598 + ... + 161468100.

It is an arithmetic number, because the mean of its divisors is an integer number (4603327428).

Almost surely, 2^81218328047 is an apocalyptic number.

81218328047 is a deficient number, since it is larger than the sum of its proper divisors (1641565657).

81218328047 is an frugal number, since it uses more digits than its factorization.

81218328047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 959 (or 731 counting only the distinct ones).

The product of its (nonzero) digits is 172032, while the sum is 44.

The spelling of 81218328047 in words is "eighty-one billion, two hundred eighteen million, three hundred twenty-eight thousand, forty-seven".