28281931 has 8 divisors (see below), whose sum is σ = 30978720. Its totient is φ = 25699968.

The previous prime is 28281907. The next prime is 28281971. The reversal of 28281931 is 13918282.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28281931 - 2⁹ = 28281419 is a prime.

It is a super-2 number, since 2×28281931² = 1599735242177522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28281901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28191 + ... + 29176.

It is an arithmetic number, because the mean of its divisors is an integer number (3872340).

Almost surely, 2^28281931 is an apocalyptic number.

28281931 is a deficient number, since it is larger than the sum of its proper divisors (2696789).

28281931 is a wasteful number, since it uses less digits than its factorization.

28281931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57413.

The product of its digits is 6912, while the sum is 34.

The square root of 28281931 is about 5318.0758738476. The cubic root of 28281931 is about 304.6746723734.

The spelling of 28281931 in words is "twenty-eight million, two hundred eighty-one thousand, nine hundred thirty-one".