81809830 has 16 divisors (see below), whose sum is σ = 147374640. Its totient is φ = 32697952.

The previous prime is 81809809. The next prime is 81809843. The reversal of 81809830 is 3890818.

It is a self number, because there is not a number n which added to its sum of digits gives 81809830.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14697 + ... + 19483.

It is an arithmetic number, because the mean of its divisors is an integer number (9210915).

Almost surely, 2^81809830 is an apocalyptic number.

81809830 is a deficient number, since it is larger than the sum of its proper divisors (65564810).

81809830 is a wasteful number, since it uses less digits than its factorization.

81809830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6503.

The product of its (nonzero) digits is 13824, while the sum is 37.

The square root of 81809830 is about 9044.8786614305. The cubic root of 81809830 is about 434.1120390023.

The spelling of 81809830 in words is "eighty-one million, eight hundred nine thousand, eight hundred thirty".