28263581 has 4 divisors (see below), whose sum is σ = 28432992. Its totient is φ = 28094172.

The previous prime is 28263577. The next prime is 28263589. The reversal of 28263581 is 18536282.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18536282 = 2 ⋅9268141.

It is a cyclic number.

It is not a de Polignac number, because 28263581 - 2² = 28263577 is a prime.

It is a super-3 number, since 3×28263581³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28263589) 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, 84455 + ... + 84788.

It is an arithmetic number, because the mean of its divisors is an integer number (7108248).

Almost surely, 2^28263581 is an apocalyptic number.

It is an amenable number.

28263581 is a deficient number, since it is larger than the sum of its proper divisors (169411).

28263581 is a wasteful number, since it uses less digits than its factorization.

28263581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169410.

The product of its digits is 23040, while the sum is 35.

The square root of 28263581 is about 5316.3503458670. The cubic root of 28263581 is about 304.6087646882.

The spelling of 28263581 in words is "twenty-eight million, two hundred sixty-three thousand, five hundred eighty-one".