91028399 has 32 divisors (see below), whose sum is σ = 118195200. Its totient is φ = 68048640.

The previous prime is 91028383. The next prime is 91028423. The reversal of 91028399 is 99382019.

It is not a de Polignac number, because 91028399 - 2⁴ = 91028383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91028309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 253382 + ... + 253740.

It is an arithmetic number, because the mean of its divisors is an integer number (3693600).

Almost surely, 2^91028399 is an apocalyptic number.

91028399 is a deficient number, since it is larger than the sum of its proper divisors (27166801).

91028399 is a wasteful number, since it uses less digits than its factorization.

91028399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503.

The product of its (nonzero) digits is 34992, while the sum is 41.

The square root of 91028399 is about 9540.8804101089. The cubic root of 91028399 is about 449.8409297852.

The spelling of 91028399 in words is "ninety-one million, twenty-eight thousand, three hundred ninety-nine".