1001821 has 2 divisors, whose sum is σ = 1001822. Its totient is φ = 1001820.

The previous prime is 1001809. The next prime is 1001831. The reversal of 1001821 is 1281001.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 765625 + 236196 = 875^2 + 486^2 .

It is a cyclic number.

It is not a de Polignac number, because 1001821 - 2¹¹ = 999773 is a prime.

It is a Chen prime.

It is a pancake number, because a pancake can be divided into 1001821 parts by 1415 straight cuts.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1001801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500910 + 500911.

It is an arithmetic number, because the mean of its divisors is an integer number (500911).

2^1001821 is an apocalyptic number.

It is an amenable number.

1001821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1001821 is an equidigital number, since it uses as much as digits as its factorization.

1001821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 1001821 is about 1000.9100858719. The cubic root of 1001821 is about 100.0606631923.

Adding to 1001821 its reverse (1281001), we get a palindrome (2282822).

The spelling of 1001821 in words is "one million, one thousand, eight hundred twenty-one".