2171021 has 2 divisors, whose sum is σ = 2171022. Its totient is φ = 2171020.

The previous prime is 2171017. The next prime is 2171077. The reversal of 2171021 is 1201712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1473796 + 697225 = 1214^2 + 835^2 .

It is a cyclic number.

It is not a de Polignac number, because 2171021 - 2² = 2171017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2170987 and 2171005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2171011) 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, 1085510 + 1085511.

It is an arithmetic number, because the mean of its divisors is an integer number (1085511).

2^2171021 is an apocalyptic number.

It is an amenable number.

2171021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2171021 is an equidigital number, since it uses as much as digits as its factorization.

2171021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 2171021 is about 1473.4384954928. The cubic root of 2171021 is about 129.4855606208.

Adding to 2171021 its reverse (1201712), we get a palindrome (3372733).

The spelling of 2171021 in words is "two million, one hundred seventy-one thousand, twenty-one".