81681828 has 24 divisors (see below), whose sum is σ = 192095232. Its totient is φ = 27012384.

The previous prime is 81681823. The next prime is 81681833. The reversal of 81681828 is 82818618.

It is an interprime number because it is at equal distance from previous prime (81681823) and next prime (81681833).

It is a self number, because there is not a number n which added to its sum of digits gives 81681828.

It is not an unprimeable number, because it can be changed into a prime (81681823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25275 + ... + 28322.

It is an arithmetic number, because the mean of its divisors is an integer number (8003968).

Almost surely, 2^81681828 is an apocalyptic number.

It is an amenable number.

81681828 is an abundant number, since it is smaller than the sum of its proper divisors (110413404).

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

81681828 is a wasteful number, since it uses less digits than its factorization.

81681828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53731 (or 53729 counting only the distinct ones).

The product of its digits is 49152, while the sum is 42.

The square root of 81681828 is about 9037.7999535285. The cubic root of 81681828 is about 433.8855127803.

The spelling of 81681828 in words is "eighty-one million, six hundred eighty-one thousand, eight hundred twenty-eight".