281921 has 2 divisors, whose sum is σ = 281922. Its totient is φ = 281920.

The previous prime is 281893. The next prime is 281923. The reversal of 281921 is 129182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255025 + 26896 = 505^2 + 164^2 .

It is a cyclic number.

It is not a de Polignac number, because 281921 - 2⁶ = 281857 is a prime.

Together with 281923, it forms a pair of twin primes.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 281921.

It is not a weakly prime, because it can be changed into another prime (281923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140960 + 140961.

It is an arithmetic number, because the mean of its divisors is an integer number (140961).

2²⁸¹⁹²¹ is an apocalyptic number.

It is an amenable number.

281921 is a deficient number, since it is larger than the sum of its proper divisors (1).

281921 is an equidigital number, since it uses as much as digits as its factorization.

281921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 23.

The square root of 281921 is about 530.9623338807. The cubic root of 281921 is about 65.5705976952.

The spelling of 281921 in words is "two hundred eighty-one thousand, nine hundred twenty-one".