81856780 has 12 divisors (see below), whose sum is σ = 171899280. Its totient is φ = 32742704.

The previous prime is 81856759. The next prime is 81856811. The reversal of 81856780 is 8765818.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2046400 + ... + 2046439.

It is an arithmetic number, because the mean of its divisors is an integer number (14324940).

Almost surely, 2^81856780 is an apocalyptic number.

It is an amenable number.

81856780 is an abundant number, since it is smaller than the sum of its proper divisors (90042500).

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

81856780 is a wasteful number, since it uses less digits than its factorization.

81856780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4092848 (or 4092846 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 43.

The square root of 81856780 is about 9047.4736805365. The cubic root of 81856780 is about 434.1950675843.

The spelling of 81856780 in words is "eighty-one million, eight hundred fifty-six thousand, seven hundred eighty".