28305981 has 24 divisors (see below), whose sum is σ = 44950464. Its totient is φ = 17021760.

The previous prime is 28305971. The next prime is 28305983. The reversal of 28305981 is 18950382.

It is not a de Polignac number, because 28305981 - 2⁹ = 28305469 is a prime.

It is a super-2 number, since 2×28305981² = 1602457120744722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28305983) 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, 12520 + ... + 14606.

It is an arithmetic number, because the mean of its divisors is an integer number (1872936).

Almost surely, 2^28305981 is an apocalyptic number.

It is an amenable number.

28305981 is a deficient number, since it is larger than the sum of its proper divisors (16644483).

28305981 is a wasteful number, since it uses less digits than its factorization.

28305981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2241 (or 2238 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 28305981 is about 5320.3365495051. The cubic root of 28305981 is about 304.7610095929.

The spelling of 28305981 in words is "twenty-eight million, three hundred five thousand, nine hundred eighty-one".