81021898912 has 48 divisors (see below), whose sum is σ = 159879025152. Its totient is φ = 40417839360.

The previous prime is 81021898897. The next prime is 81021898921. The reversal of 81021898912 is 21989812018.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39272793 + ... + 39274855.

It is an arithmetic number, because the mean of its divisors is an integer number (3330813024).

Almost surely, 2^81021898912 is an apocalyptic number.

It is an amenable number.

81021898912 is a deficient number, since it is larger than the sum of its proper divisors (78857126240).

81021898912 is a wasteful number, since it uses less digits than its factorization.

81021898912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4301 (or 4293 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 49.

The spelling of 81021898912 in words is "eighty-one billion, twenty-one million, eight hundred ninety-eight thousand, nine hundred twelve".