28781315 has 4 divisors (see below), whose sum is σ = 34537584. Its totient is φ = 23025048.

The previous prime is 28781297. The next prime is 28781317. The reversal of 28781315 is 51318782.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51318782 = 2 ⋅25659391.

It is a cyclic number.

It is not a de Polignac number, because 28781315 - 2⁶ = 28781251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28781317) 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, 2878127 + ... + 2878136.

It is an arithmetic number, because the mean of its divisors is an integer number (8634396).

Almost surely, 2^28781315 is an apocalyptic number.

28781315 is a deficient number, since it is larger than the sum of its proper divisors (5756269).

28781315 is an equidigital number, since it uses as much as digits as its factorization.

28781315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5756268.

The product of its digits is 13440, while the sum is 35.

The square root of 28781315 is about 5364.8219914551. The cubic root of 28781315 is about 306.4574693028.

The spelling of 28781315 in words is "twenty-eight million, seven hundred eighty-one thousand, three hundred fifteen".