28311931 has 4 divisors (see below), whose sum is σ = 28970392. Its totient is φ = 27653472.

The previous prime is 28311901. The next prime is 28311947. The reversal of 28311931 is 13911382.

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

It is not a de Polignac number, because 28311931 - 2⁹ = 28311419 is a prime.

It is a super-2 number, since 2×28311931² = 1603130873897522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28311931.

It is not an unprimeable number, because it can be changed into a prime (28311901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 329166 + ... + 329251.

It is an arithmetic number, because the mean of its divisors is an integer number (7242598).

Almost surely, 2^28311931 is an apocalyptic number.

28311931 is a deficient number, since it is larger than the sum of its proper divisors (658461).

28311931 is an equidigital number, since it uses as much as digits as its factorization.

28311931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 658460.

The product of its digits is 1296, while the sum is 28.

The square root of 28311931 is about 5320.8956952754. The cubic root of 28311931 is about 304.7823619820.

The spelling of 28311931 in words is "twenty-eight million, three hundred eleven thousand, nine hundred thirty-one".