81755218 has 8 divisors (see below), whose sum is σ = 123122160. Its totient is φ = 40714500.

The previous prime is 81755173. The next prime is 81755239. The reversal of 81755218 is 81255718.

It is a sphenic number, since it is the product of 3 distinct primes.

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, 80928 + ... + 81931.

It is an arithmetic number, because the mean of its divisors is an integer number (15390270).

Almost surely, 2^81755218 is an apocalyptic number.

81755218 is a deficient number, since it is larger than the sum of its proper divisors (41366942).

81755218 is a wasteful number, since it uses less digits than its factorization.

81755218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163112.

The product of its digits is 22400, while the sum is 37.

The square root of 81755218 is about 9041.8592114675. The cubic root of 81755218 is about 434.0154206049.

Subtracting from 81755218 its reverse (81255718), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 81755218 in words is "eighty-one million, seven hundred fifty-five thousand, two hundred eighteen".