81808245 has 16 divisors (see below), whose sum is σ = 145437120. Its totient is φ = 43630992.

The previous prime is 81808229. The next prime is 81808289. The reversal of 81808245 is 54280818.

It is not a de Polignac number, because 81808245 - 2⁴ = 81808229 is a prime.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 302859 + ... + 303128.

It is an arithmetic number, because the mean of its divisors is an integer number (9089820).

Almost surely, 2^81808245 is an apocalyptic number.

It is an amenable number.

81808245 is a deficient number, since it is larger than the sum of its proper divisors (63628875).

81808245 is a wasteful number, since it uses less digits than its factorization.

81808245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 606001 (or 605995 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 36.

The square root of 81808245 is about 9044.7910423624. The cubic root of 81808245 is about 434.1092354597.

The spelling of 81808245 in words is "eighty-one million, eight hundred eight thousand, two hundred forty-five".