28430991 has 24 divisors (see below), whose sum is σ = 42959280. Its totient is φ = 18095616.

The previous prime is 28430989. The next prime is 28431019. The reversal of 28430991 is 19903482.

It is not a de Polignac number, because 28430991 - 2¹ = 28430989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28430971) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24756 + ... + 25878.

It is an arithmetic number, because the mean of its divisors is an integer number (1789970).

Almost surely, 2^28430991 is an apocalyptic number.

28430991 is a deficient number, since it is larger than the sum of its proper divisors (14528289).

28430991 is a wasteful number, since it uses less digits than its factorization.

28430991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1255 (or 1252 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 28430991 is about 5332.0719237460. The cubic root of 28430991 is about 305.2089976660.

The spelling of 28430991 in words is "twenty-eight million, four hundred thirty thousand, nine hundred ninety-one".