28061521 has 4 divisors (see below), whose sum is σ = 28537200. Its totient is φ = 27585844.

The previous prime is 28061519. The next prime is 28061557. The reversal of 28061521 is 12516082.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12516082 = 2 ⋅6258041.

It is a cyclic number.

It is not a de Polignac number, because 28061521 - 2¹ = 28061519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28061321) 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, 237751 + ... + 237868.

It is an arithmetic number, because the mean of its divisors is an integer number (7134300).

Almost surely, 2^28061521 is an apocalyptic number.

It is an amenable number.

28061521 is a deficient number, since it is larger than the sum of its proper divisors (475679).

28061521 is an equidigital number, since it uses as much as digits as its factorization.

28061521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475678.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 28061521 is about 5297.3126205653. The cubic root of 28061521 is about 303.8811321110.

It can be divided in two parts, 28061 and 521, that added together give a palindrome (28582).

The spelling of 28061521 in words is "twenty-eight million, sixty-one thousand, five hundred twenty-one".