1591021 has 2 divisors, whose sum is σ = 1591022. Its totient is φ = 1591020.

The previous prime is 1591001. The next prime is 1591033. The reversal of 1591021 is 1201951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1590121 + 900 = 1261^2 + 30^2 .

It is a cyclic number.

It is not a de Polignac number, because 1591021 - 2⁷ = 1590893 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1591021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1591001) 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, 795510 + 795511.

It is an arithmetic number, because the mean of its divisors is an integer number (795511).

2^1591021 is an apocalyptic number.

It is an amenable number.

1591021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1591021 is an equidigital number, since it uses as much as digits as its factorization.

1591021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 90, while the sum is 19.

The square root of 1591021 is about 1261.3568091543. The cubic root of 1591021 is about 116.7415093471.

Adding to 1591021 its reverse (1201951), we get a palindrome (2792972).

It can be divided in two parts, 15910 and 21, that added together give a triangular number (15931 = T₁₇₈).

The spelling of 1591021 in words is "one million, five hundred ninety-one thousand, twenty-one".