81205306 has 64 divisors (see below), whose sum is σ = 159344640. Its totient is φ = 30170880.

The previous prime is 81205261. The next prime is 81205321. The reversal of 81205306 is 60350218.

It is a happy 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 31 ways as a sum of consecutive naturals, for example, 208560 + ... + 208948.

It is an arithmetic number, because the mean of its divisors is an integer number (2489760).

Almost surely, 2^81205306 is an apocalyptic number.

81205306 is a deficient number, since it is larger than the sum of its proper divisors (78139334).

81205306 is a wasteful number, since it uses less digits than its factorization.

81205306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 479.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 81205306 is about 9011.3986705727. The cubic root of 81205306 is about 433.0401213030.

The spelling of 81205306 in words is "eighty-one million, two hundred five thousand, three hundred six".