28112981 has 6 divisors (see below), whose sum is σ = 30442050. Its totient is φ = 25950288.

The previous prime is 28112879. The next prime is 28113011. The reversal of 28112981 is 18921182.

It can be written as a sum of positive squares in 3 ways, for example, as 128881 + 27984100 = 359^2 + 5290^2 .

It is a de Polignac number, because none of the positive numbers 2^k-28112981 is a prime.

It is a super-2 number, since 2×28112981² = 1580679401412722, 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 (28117981) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 83006 + ... + 83343.

It is an arithmetic number, because the mean of its divisors is an integer number (5073675).

Almost surely, 2^28112981 is an apocalyptic number.

It is an amenable number.

28112981 is a deficient number, since it is larger than the sum of its proper divisors (2329069).

28112981 is a wasteful number, since it uses less digits than its factorization.

28112981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166375 (or 166362 counting only the distinct ones).

The product of its digits is 2304, while the sum is 32.

The square root of 28112981 is about 5302.1675756241. The cubic root of 28112981 is about 304.0667739111.

The spelling of 28112981 in words is "twenty-eight million, one hundred twelve thousand, nine hundred eighty-one".