28355531 has 2 divisors, whose sum is σ = 28355532. Its totient is φ = 28355530.

The previous prime is 28355513. The next prime is 28355563. The reversal of 28355531 is 13555382.

Together with previous prime (28355513) it forms an Ormiston pair, because they use the same digits, order apart.

It is an a-pointer prime, because the next prime (28355563) can be obtained adding 28355531 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28355531 - 2¹⁰ = 28354507 is a prime.

It is a super-3 number, since 3×28355531³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (28355501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14177765 + 14177766.

It is an arithmetic number, because the mean of its divisors is an integer number (14177766).

Almost surely, 2^28355531 is an apocalyptic number.

28355531 is a deficient number, since it is larger than the sum of its proper divisors (1).

28355531 is an equidigital number, since it uses as much as digits as its factorization.

28355531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18000, while the sum is 32.

The square root of 28355531 is about 5324.9911737016. The cubic root of 28355531 is about 304.9387353432.

The spelling of 28355531 in words is "twenty-eight million, three hundred fifty-five thousand, five hundred thirty-one".