28515131 has 4 divisors (see below), whose sum is σ = 29210664. Its totient is φ = 27819600.

The previous prime is 28515119. The next prime is 28515139. The reversal of 28515131 is 13151582.

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: 13151582 = 2 ⋅6575791.

It is a cyclic number.

It is not a de Polignac number, because 28515131 - 2¹⁴ = 28498747 is a prime.

It is a super-2 number, since 2×28515131² = 1626225391894322, 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 28515131.

It is not an unprimeable number, because it can be changed into a prime (28515139) 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, 347705 + ... + 347786.

It is an arithmetic number, because the mean of its divisors is an integer number (7302666).

Almost surely, 2^28515131 is an apocalyptic number.

28515131 is a deficient number, since it is larger than the sum of its proper divisors (695533).

28515131 is an equidigital number, since it uses as much as digits as its factorization.

28515131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 695532.

The product of its digits is 1200, while the sum is 26.

The square root of 28515131 is about 5339.9560859618. The cubic root of 28515131 is about 305.5097843849.

The spelling of 28515131 in words is "twenty-eight million, five hundred fifteen thousand, one hundred thirty-one".