81743820 has 48 divisors (see below), whose sum is σ = 242349408. Its totient is φ = 20515840.

The previous prime is 81743801. The next prime is 81743821. The reversal of 81743820 is 2834718.

It is not an unprimeable number, because it can be changed into a prime (81743821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39051 + ... + 41090.

It is an arithmetic number, because the mean of its divisors is an integer number (5048946).

Almost surely, 2^81743820 is an apocalyptic number.

It is an amenable number.

81743820 is an abundant number, since it is smaller than the sum of its proper divisors (160605588).

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

81743820 is a wasteful number, since it uses less digits than its factorization.

81743820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80170 (or 80168 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 81743820 is about 9041.2288987726. The cubic root of 81743820 is about 433.9952500772.

The spelling of 81743820 in words is "eighty-one million, seven hundred forty-three thousand, eight hundred twenty".