28609561 has 4 divisors (see below), whose sum is σ = 28656400. Its totient is φ = 28562724.

The previous prime is 28609543. The next prime is 28609583. The reversal of 28609561 is 16590682.

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 28609561 - 2⁷ = 28609433 is a prime.

It is a super-2 number, since 2×28609561² = 1637013961225442, 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 28609561.

It is not an unprimeable number, because it can be changed into a prime (28609541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22491 + ... + 23728.

It is an arithmetic number, because the mean of its divisors is an integer number (7164100).

Almost surely, 2^28609561 is an apocalyptic number.

It is an amenable number.

28609561 is a deficient number, since it is larger than the sum of its proper divisors (46839).

28609561 is an equidigital number, since it uses as much as digits as its factorization.

28609561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46838.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 28609561 is about 5348.7906109699. The cubic root of 28609561 is about 305.8466523430.

It can be divided in two parts, 2860 and 9561, that added together give a palindrome (12421).

The spelling of 28609561 in words is "twenty-eight million, six hundred nine thousand, five hundred sixty-one".