28664581 has 4 divisors (see below), whose sum is σ = 31270464. Its totient is φ = 26058700.

The previous prime is 28664579. The next prime is 28664593. The reversal of 28664581 is 18546682.

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 28664581 - 2¹ = 28664579 is a prime.

It is a super-2 number, since 2×28664581² = 1643316407811122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28664981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1302925 + ... + 1302946.

It is an arithmetic number, because the mean of its divisors is an integer number (7817616).

Almost surely, 2^28664581 is an apocalyptic number.

It is an amenable number.

28664581 is a deficient number, since it is larger than the sum of its proper divisors (2605883).

28664581 is a wasteful number, since it uses less digits than its factorization.

28664581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2605882.

The product of its digits is 92160, while the sum is 40.

The square root of 28664581 is about 5353.9313592910. The cubic root of 28664581 is about 306.0425880890.

It can be divided in two parts, 2866 and 4581, that added together give a palindrome (7447).

The spelling of 28664581 in words is "twenty-eight million, six hundred sixty-four thousand, five hundred eighty-one".