28131515 has 16 divisors (see below), whose sum is σ = 36015840. Its totient is φ = 21020160.

The previous prime is 28131473. The next prime is 28131527. The reversal of 28131515 is 51513182.

It is a happy number.

It is not a de Polignac number, because 28131515 - 2¹⁶ = 28065979 is a prime.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 10625 + ... + 13005.

It is an arithmetic number, because the mean of its divisors is an integer number (2250990).

Almost surely, 2^28131515 is an apocalyptic number.

28131515 is a deficient number, since it is larger than the sum of its proper divisors (7884325).

28131515 is a wasteful number, since it uses less digits than its factorization.

28131515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2542.

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

The square root of 28131515 is about 5303.9150634225. The cubic root of 28131515 is about 304.1335797708.

Adding to 28131515 its reverse (51513182), we get a palindrome (79644697).

The spelling of 28131515 in words is "twenty-eight million, one hundred thirty-one thousand, five hundred fifteen".