81121996828 has 6 divisors (see below), whose sum is σ = 141963494456. Its totient is φ = 40560998412.

The previous prime is 81121996819. The next prime is 81121996829. The reversal of 81121996828 is 82869912118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81121996829) by changing a digit.

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 as a sum of consecutive naturals, namely, 10140249600 + ... + 10140249607.

Almost surely, 2^81121996828 is an apocalyptic number.

It is an amenable number.

81121996828 is a deficient number, since it is larger than the sum of its proper divisors (60841497628).

81121996828 is a wasteful number, since it uses less digits than its factorization.

81121996828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20280499211 (or 20280499209 counting only the distinct ones).

The product of its digits is 995328, while the sum is 55.

The spelling of 81121996828 in words is "eighty-one billion, one hundred twenty-one million, nine hundred ninety-six thousand, eight hundred twenty-eight".