28390331 has 4 divisors (see below), whose sum is σ = 28451592. Its totient is φ = 28329072.

The previous prime is 28390321. The next prime is 28390337. The reversal of 28390331 is 13309382.

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

It is a cyclic number.

It is not a de Polignac number, because 28390331 - 2⁶ = 28390267 is a prime.

It is a super-2 number, since 2×28390331² = 1612021788579122, 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 = 28390294 and 28390303.

It is not an unprimeable number, because it can be changed into a prime (28390337) 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, 29930 + ... + 30863.

It is an arithmetic number, because the mean of its divisors is an integer number (7112898).

Almost surely, 2^28390331 is an apocalyptic number.

28390331 is a deficient number, since it is larger than the sum of its proper divisors (61261).

28390331 is an equidigital number, since it uses as much as digits as its factorization.

28390331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61260.

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 28390331 is about 5328.2577828029. The cubic root of 28390331 is about 305.0634321172.

The spelling of 28390331 in words is "twenty-eight million, three hundred ninety thousand, three hundred thirty-one".