28287981 has 8 divisors (see below), whose sum is σ = 41908160. Its totient is φ = 18858636.

The previous prime is 28287929. The next prime is 28288019. The reversal of 28287981 is 18978282.

It is a happy number.

It is not a de Polignac number, because 28287981 - 2¹⁰ = 28286957 is a prime.

It is a super-2 number, since 2×28287981² = 1600419738112722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28287481) 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 7 ways as a sum of consecutive naturals, for example, 523825 + ... + 523878.

It is an arithmetic number, because the mean of its divisors is an integer number (5238520).

Almost surely, 2^28287981 is an apocalyptic number.

It is an amenable number.

28287981 is a deficient number, since it is larger than the sum of its proper divisors (13620179).

28287981 is a wasteful number, since it uses less digits than its factorization.

28287981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1047712 (or 1047706 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 28287981 is about 5318.6446581813. The cubic root of 28287981 is about 304.6963959059.

The spelling of 28287981 in words is "twenty-eight million, two hundred eighty-seven thousand, nine hundred eighty-one".