28308431 has 4 divisors (see below), whose sum is σ = 28322352. Its totient is φ = 28294512.

The previous prime is 28308419. The next prime is 28308443. The reversal of 28308431 is 13480382.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13480382 = 2 ⋅6740191.

It is an interprime number because it is at equal distance from previous prime (28308419) and next prime (28308443).

It is a cyclic number.

It is not a de Polignac number, because 28308431 - 2²² = 24114127 is a prime.

It is a super-2 number, since 2×28308431² = 1602734531363522, 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 = 28308394 and 28308403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28388431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3251 + ... + 8196.

It is an arithmetic number, because the mean of its divisors is an integer number (7080588).

Almost surely, 2^28308431 is an apocalyptic number.

28308431 is a deficient number, since it is larger than the sum of its proper divisors (13921).

28308431 is a wasteful number, since it uses less digits than its factorization.

28308431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13920.

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 28308431 is about 5320.5667931152. The cubic root of 28308431 is about 304.7698021155.

The spelling of 28308431 in words is "twenty-eight million, three hundred eight thousand, four hundred thirty-one".