81555208 has 24 divisors (see below), whose sum is σ = 177882750. Its totient is φ = 34952064.

The previous prime is 81555197. The next prime is 81555233. The reversal of 81555208 is 80255518.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 46485124 + 35070084 = 6818^2 + 5922^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 103633 + ... + 104416.

Almost surely, 2^81555208 is an apocalyptic number.

It is an amenable number.

81555208 is an abundant number, since it is smaller than the sum of its proper divisors (96327542).

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

81555208 is a wasteful number, since it uses less digits than its factorization.

81555208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208069 (or 208058 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 34.

The square root of 81555208 is about 9030.7922133111. The cubic root of 81555208 is about 433.6611993382.

The spelling of 81555208 in words is "eighty-one million, five hundred fifty-five thousand, two hundred eight".