81785216 has 32 divisors (see below), whose sum is σ = 163469280. Its totient is φ = 40757760.

The previous prime is 81785203. The next prime is 81785233. The reversal of 81785216 is 61258718.

It is a tau number, because it is divible by the number of its divisors (32).

It is a self number, because there is not a number n which added to its sum of digits gives 81785216.

It is a congruent number.

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, 46106 + ... + 47846.

It is an arithmetic number, because the mean of its divisors is an integer number (5108415).

Almost surely, 2^81785216 is an apocalyptic number.

It is an amenable number.

81785216 is a deficient number, since it is larger than the sum of its proper divisors (81684064).

81785216 is a wasteful number, since it uses less digits than its factorization.

81785216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2122 (or 2110 counting only the distinct ones).

The product of its digits is 26880, while the sum is 38.

The square root of 81785216 is about 9043.5178995787. The cubic root of 81785216 is about 434.0684977574.

The spelling of 81785216 in words is "eighty-one million, seven hundred eighty-five thousand, two hundred sixteen".