28312931 has 4 divisors (see below), whose sum is σ = 29543952. Its totient is φ = 27081912.

The previous prime is 28312901. The next prime is 28312943. The reversal of 28312931 is 13921382.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28312931 is a prime.

It is a super-2 number, since 2×28312931² = 1603244123621522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28312894 and 28312903.

It is not an unprimeable number, because it can be changed into a prime (28312901) 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, 615476 + ... + 615521.

It is an arithmetic number, because the mean of its divisors is an integer number (7385988).

Almost surely, 2^28312931 is an apocalyptic number.

28312931 is a deficient number, since it is larger than the sum of its proper divisors (1231021).

28312931 is a wasteful number, since it uses less digits than its factorization.

28312931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1231020.

The product of its digits is 2592, while the sum is 29.

The square root of 28312931 is about 5320.9896635870. The cubic root of 28312931 is about 304.7859503252.

The spelling of 28312931 in words is "twenty-eight million, three hundred twelve thousand, nine hundred thirty-one".