81820828 has 6 divisors (see below), whose sum is σ = 143186456. Its totient is φ = 40910412.

The previous prime is 81820793. The next prime is 81820841. The reversal of 81820828 is 82802818.

It is a congruent 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 as a sum of consecutive naturals, namely, 10227600 + ... + 10227607.

Almost surely, 2^81820828 is an apocalyptic number.

It is an amenable number.

81820828 is a deficient number, since it is larger than the sum of its proper divisors (61365628).

81820828 is a wasteful number, since it uses less digits than its factorization.

81820828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20455211 (or 20455209 counting only the distinct ones).

The product of its (nonzero) digits is 16384, while the sum is 37.

The square root of 81820828 is about 9045.4866093539. The cubic root of 81820828 is about 434.1314912298.

The spelling of 81820828 in words is "eighty-one million, eight hundred twenty thousand, eight hundred twenty-eight".