1641821 has 2 divisors, whose sum is σ = 1641822. Its totient is φ = 1641820.

The previous prime is 1641817. The next prime is 1641833. The reversal of 1641821 is 1281461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1406596 + 235225 = 1186^2 + 485^2 .

It is a cyclic number.

It is not a de Polignac number, because 1641821 - 2² = 1641817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1641811) 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, 820910 + 820911.

It is an arithmetic number, because the mean of its divisors is an integer number (820911).

2^1641821 is an apocalyptic number.

It is an amenable number.

1641821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1641821 is an equidigital number, since it uses as much as digits as its factorization.

1641821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 384, while the sum is 23.

The square root of 1641821 is about 1281.3356312848. The cubic root of 1641821 is about 117.9710021630.

It can be divided in two parts, 1641 and 821, that multiplied together give a triangular number (1347261 = T₁₆₄₁).

The spelling of 1641821 in words is "one million, six hundred forty-one thousand, eight hundred twenty-one".