1291021 has 2 divisors, whose sum is σ = 1291022. Its totient is φ = 1291020.

The previous prime is 1291019. The next prime is 1291063. The reversal of 1291021 is 1201921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 835396 + 455625 = 914^2 + 675^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291021 - 2¹ = 1291019 is a prime.

Together with 1291019, it forms a pair of twin primes.

1291021 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1290986 and 1291004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645510 + 645511.

It is an arithmetic number, because the mean of its divisors is an integer number (645511).

2^1291021 is an apocalyptic number.

It is an amenable number.

1291021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291021 is an equidigital number, since it uses as much as digits as its factorization.

1291021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 1291021 is about 1136.2310504470. The cubic root of 1291021 is about 108.8874353470.

Adding to 1291021 its reverse (1201921), we get a palindrome (2492942).

The spelling of 1291021 in words is "one million, two hundred ninety-one thousand, twenty-one".