1801021 has 2 divisors, whose sum is σ = 1801022. Its totient is φ = 1801020.

The previous prime is 1801013. The next prime is 1801039. The reversal of 1801021 is 1201081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1792921 + 8100 = 1339^2 + 90^2 .

It is a cyclic number.

It is not a de Polignac number, because 1801021 - 2³ = 1801013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1800992 and 1801010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1801091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 900510 + 900511.

It is an arithmetic number, because the mean of its divisors is an integer number (900511).

2^1801021 is an apocalyptic number.

It is an amenable number.

1801021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1801021 is an equidigital number, since it uses as much as digits as its factorization.

1801021 is an odious number, because the sum of its binary digits is odd.

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

The square root of 1801021 is about 1342.0212367917. The cubic root of 1801021 is about 121.6670352984.

The spelling of 1801021 in words is "one million, eight hundred one thousand, twenty-one".