91028905 has 24 divisors (see below), whose sum is σ = 126403200. Its totient is φ = 62710560.

The previous prime is 91028891. The next prime is 91028909. The reversal of 91028905 is 50982019.

It is not a de Polignac number, because 91028905 - 2²¹ = 88931753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91028909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7536 + ... + 15454.

It is an arithmetic number, because the mean of its divisors is an integer number (5266800).

Almost surely, 2^91028905 is an apocalyptic number.

91028905 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

It is an amenable number.

91028905 is a deficient number, since it is larger than the sum of its proper divisors (35374295).

91028905 is a wasteful number, since it uses less digits than its factorization.

91028905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7965 (or 7954 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 91028905 is about 9540.9069275410. The cubic root of 91028905 is about 449.8417632947.

The spelling of 91028905 in words is "ninety-one million, twenty-eight thousand, nine hundred five".