28091881 has 2 divisors, whose sum is σ = 28091882. Its totient is φ = 28091880.

The previous prime is 28091873. The next prime is 28091893. The reversal of 28091881 is 18819082.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27825625 + 266256 = 5275^2 + 516^2 .

It is a cyclic number.

It is not a de Polignac number, because 28091881 - 2³ = 28091873 is a prime.

It is a super-2 number, since 2×28091881² = 1578307556236322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 28091881.

It is not a weakly prime, because it can be changed into another prime (28091801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14045940 + 14045941.

It is an arithmetic number, because the mean of its divisors is an integer number (14045941).

Almost surely, 2^28091881 is an apocalyptic number.

It is an amenable number.

28091881 is a deficient number, since it is larger than the sum of its proper divisors (1).

28091881 is an equidigital number, since it uses as much as digits as its factorization.

28091881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 28091881 is about 5300.1774498596. The cubic root of 28091881 is about 303.9906831459.

The spelling of 28091881 in words is "twenty-eight million, ninety-one thousand, eight hundred eighty-one".