81823820 has 24 divisors (see below), whose sum is σ = 185048304. Its totient is φ = 30211776.

The previous prime is 81823813. The next prime is 81823831. The reversal of 81823820 is 2832818.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 157094 + ... + 157613.

It is an arithmetic number, because the mean of its divisors is an integer number (7710346).

Almost surely, 2^81823820 is an apocalyptic number.

It is an amenable number.

81823820 is an abundant number, since it is smaller than the sum of its proper divisors (103224484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81823820 is a wasteful number, since it uses less digits than its factorization.

81823820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314729 (or 314727 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 81823820 is about 9045.6519941904. The cubic root of 81823820 is about 434.1367828962.

The spelling of 81823820 in words is "eighty-one million, eight hundred twenty-three thousand, eight hundred twenty".