28563261 has 4 divisors (see below), whose sum is σ = 38084352. Its totient is φ = 19042172.

The previous prime is 28563253. The next prime is 28563277. The reversal of 28563261 is 16236582.

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 28563261 - 2³ = 28563253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28563211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4760541 + ... + 4760546.

It is an arithmetic number, because the mean of its divisors is an integer number (9521088).

Almost surely, 2^28563261 is an apocalyptic number.

It is an amenable number.

28563261 is a deficient number, since it is larger than the sum of its proper divisors (9521091).

28563261 is an equidigital number, since it uses as much as digits as its factorization.

28563261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9521090.

The product of its digits is 17280, while the sum is 33.

The square root of 28563261 is about 5344.4607772908. The cubic root of 28563261 is about 305.6815752927.

It can be divided in two parts, 285 and 63261, that added together give a triangular number (63546 = T₃₅₆).

The spelling of 28563261 in words is "twenty-eight million, five hundred sixty-three thousand, two hundred sixty-one".