81855206 has 8 divisors (see below), whose sum is σ = 128121264. Its totient is φ = 39148120.

The previous prime is 81855199. The next prime is 81855209. The reversal of 81855206 is 60255818.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81855209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 889685 + ... + 889776.

It is an arithmetic number, because the mean of its divisors is an integer number (16015158).

Almost surely, 2^81855206 is an apocalyptic number.

81855206 is a deficient number, since it is larger than the sum of its proper divisors (46266058).

81855206 is a wasteful number, since it uses less digits than its factorization.

81855206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1779486.

The product of its (nonzero) digits is 19200, while the sum is 35.

The square root of 81855206 is about 9047.3866945102. The cubic root of 81855206 is about 434.1922845632.

The spelling of 81855206 in words is "eighty-one million, eight hundred fifty-five thousand, two hundred six".