1804921 has 2 divisors, whose sum is σ = 1804922. Its totient is φ = 1804920.

The previous prime is 1804919. The next prime is 1804927. The reversal of 1804921 is 1294081.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1690000 + 114921 = 1300^2 + 339^2 .

It is an emirp because it is prime and its reverse (1294081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1804921 - 2¹ = 1804919 is a prime.

Together with 1804919, it forms a pair of twin primes.

1804921 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1804927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 902460 + 902461.

It is an arithmetic number, because the mean of its divisors is an integer number (902461).

2^1804921 is an apocalyptic number.

It is an amenable number.

1804921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1804921 is an equidigital number, since it uses as much as digits as its factorization.

1804921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 1804921 is about 1343.4734831771. The cubic root of 1804921 is about 121.7547928070.

The spelling of 1804921 in words is "one million, eight hundred four thousand, nine hundred twenty-one".