28281691 has 2 divisors, whose sum is σ = 28281692. Its totient is φ = 28281690.

The previous prime is 28281689. The next prime is 28281731. The reversal of 28281691 is 19618282.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28281691 - 2¹ = 28281689 is a prime.

Together with 28281689, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 28281691.

It is not a weakly prime, because it can be changed into another prime (28281601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14140845 + 14140846.

It is an arithmetic number, because the mean of its divisors is an integer number (14140846).

Almost surely, 2^28281691 is an apocalyptic number.

28281691 is a deficient number, since it is larger than the sum of its proper divisors (1).

28281691 is an equidigital number, since it uses as much as digits as its factorization.

28281691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 37.

The square root of 28281691 is about 5318.0533092477. The cubic root of 28281691 is about 304.6738105495.

The spelling of 28281691 in words is "twenty-eight million, two hundred eighty-one thousand, six hundred ninety-one".