28231999 has 4 divisors (see below), whose sum is σ = 28995064. Its totient is φ = 27468936.

The previous prime is 28231969. The next prime is 28232003. The reversal of 28231999 is 99913282.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28231999 - 2⁹ = 28231487 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 (28231919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 381477 + ... + 381550.

It is an arithmetic number, because the mean of its divisors is an integer number (7248766).

Almost surely, 2^28231999 is an apocalyptic number.

28231999 is a deficient number, since it is larger than the sum of its proper divisors (763065).

28231999 is an equidigital number, since it uses as much as digits as its factorization.

28231999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 763064.

The product of its digits is 69984, while the sum is 43.

The square root of 28231999 is about 5313.3792448874. The cubic root of 28231999 is about 304.4952648047.

The spelling of 28231999 in words is "twenty-eight million, two hundred thirty-one thousand, nine hundred ninety-nine".