81178720148 has 12 divisors (see below), whose sum is σ = 146961476340. Its totient is φ = 39189726912.

The previous prime is 81178720109. The next prime is 81178720157. The reversal of 81178720148 is 84102787118.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 56483226244 + 24695493904 = 237662^2 + 157148^2 .

It is a super-4 number, since 4×81178720148⁴ (a number of 45 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 349908161 + ... + 349908392.

It is an arithmetic number, because the mean of its divisors is an integer number (12246789695).

Almost surely, 2^81178720148 is an apocalyptic number.

It is an amenable number.

81178720148 is a deficient number, since it is larger than the sum of its proper divisors (65782756192).

81178720148 is a wasteful number, since it uses less digits than its factorization.

81178720148 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699816586 (or 699816584 counting only the distinct ones).

The product of its (nonzero) digits is 200704, while the sum is 47.

The spelling of 81178720148 in words is "eighty-one billion, one hundred seventy-eight million, seven hundred twenty thousand, one hundred forty-eight".