28345581 has 18 divisors (see below), whose sum is σ = 45005870. Its totient is φ = 17178480.

The previous prime is 28345571. The next prime is 28345601. The reversal of 28345581 is 18554382.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17015625 + 11329956 = 4125^2 + 3366^2 .

It is not a de Polignac number, because 28345581 - 2¹⁹ = 27821293 is a prime.

It is a super-2 number, since 2×28345581² = 1606943924455122, 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 (28345561) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11926 + ... + 14103.

Almost surely, 2^28345581 is an apocalyptic number.

It is an amenable number.

28345581 is a deficient number, since it is larger than the sum of its proper divisors (16660289).

28345581 is a wasteful number, since it uses less digits than its factorization.

28345581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26057 (or 26043 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The square root of 28345581 is about 5324.0568178786. The cubic root of 28345581 is about 304.9030633447.

The spelling of 28345581 in words is "twenty-eight million, three hundred forty-five thousand, five hundred eighty-one".