28531213 has 4 divisors (see below), whose sum is σ = 28957120. Its totient is φ = 28105308.

The previous prime is 28531189. The next prime is 28531249. The reversal of 28531213 is 31213582.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28531213 - 2⁹ = 28530701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28531813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 212853 + ... + 212986.

It is an arithmetic number, because the mean of its divisors is an integer number (7239280).

Almost surely, 2^28531213 is an apocalyptic number.

It is an amenable number.

28531213 is a deficient number, since it is larger than the sum of its proper divisors (425907).

28531213 is an equidigital number, since it uses as much as digits as its factorization.

28531213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 425906.

The product of its digits is 1440, while the sum is 25.

The square root of 28531213 is about 5341.4616913351. The cubic root of 28531213 is about 305.5672075238.

Adding to 28531213 its reverse (31213582), we get a palindrome (59744795).

The spelling of 28531213 in words is "twenty-eight million, five hundred thirty-one thousand, two hundred thirteen".