81028905 has 16 divisors (see below), whose sum is σ = 131424000. Its totient is φ = 42622848.

The previous prime is 81028903. The next prime is 81028907. The reversal of 81028905 is 50982018.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81028903) and next prime (81028907).

It is not a de Polignac number, because 81028905 - 2¹ = 81028903 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81028903) by changing a digit.

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, 35905 + ... + 38094.

It is an arithmetic number, because the mean of its divisors is an integer number (8214000).

Almost surely, 2^81028905 is an apocalyptic number.

It is an amenable number.

81028905 is a deficient number, since it is larger than the sum of its proper divisors (50395095).

81028905 is a wasteful number, since it uses less digits than its factorization.

81028905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74080.

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 81028905 is about 9001.6056900977. The cubic root of 81028905 is about 432.7263319144.

The spelling of 81028905 in words is "eighty-one million, twenty-eight thousand, nine hundred five".