28313931 has 4 divisors (see below), whose sum is σ = 37751912. Its totient is φ = 18875952.

The previous prime is 28313921. The next prime is 28313939. The reversal of 28313931 is 13931382.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 28313931 - 2¹¹ = 28311883 is a prime.

It is a super-2 number, since 2×28313931² = 1603357377345522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28313939) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4718986 + ... + 4718991.

It is an arithmetic number, because the mean of its divisors is an integer number (9437978).

Almost surely, 2^28313931 is an apocalyptic number.

28313931 is a deficient number, since it is larger than the sum of its proper divisors (9437981).

28313931 is an equidigital number, since it uses as much as digits as its factorization.

28313931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9437980.

The product of its digits is 3888, while the sum is 30.

The square root of 28313931 is about 5321.0836302392. The cubic root of 28313931 is about 304.7895385839.

The spelling of 28313931 in words is "twenty-eight million, three hundred thirteen thousand, nine hundred thirty-one".