28816581 has 16 divisors (see below), whose sum is σ = 40824000. Its totient is φ = 18018048.

The previous prime is 28816561. The next prime is 28816589. The reversal of 28816581 is 18561882.

It is not a de Polignac number, because 28816581 - 2⁵ = 28816549 is a prime.

It is a super-2 number, since 2×28816581² = 1660790681059122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28816589) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16990 + ... + 18608.

It is an arithmetic number, because the mean of its divisors is an integer number (2551500).

Almost surely, 2^28816581 is an apocalyptic number.

It is an amenable number.

28816581 is a deficient number, since it is larger than the sum of its proper divisors (12007419).

28816581 is a wasteful number, since it uses less digits than its factorization.

28816581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1988.

The product of its digits is 30720, while the sum is 39.

The square root of 28816581 is about 5368.1077671746. The cubic root of 28816581 is about 306.5825865641.

The spelling of 28816581 in words is "twenty-eight million, eight hundred sixteen thousand, five hundred eighty-one".