281221609 has 2 divisors, whose sum is σ = 281221610. Its totient is φ = 281221608.

The previous prime is 281221607. The next prime is 281221627. The reversal of 281221609 is 906122182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 280227600 + 994009 = 16740^2 + 997^2 .

It is a cyclic number.

It is not a de Polignac number, because 281221609 - 2¹ = 281221607 is a prime.

Together with 281221607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (281221601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140610804 + 140610805.

It is an arithmetic number, because the mean of its divisors is an integer number (140610805).

Almost surely, 2^281221609 is an apocalyptic number.

It is an amenable number.

281221609 is a deficient number, since it is larger than the sum of its proper divisors (1).

281221609 is an equidigital number, since it uses as much as digits as its factorization.

281221609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 281221609 is about 16769.6633538065. The cubic root of 281221609 is about 655.1633017455.

The spelling of 281221609 in words is "two hundred eighty-one million, two hundred twenty-one thousand, six hundred nine".