1803721921 has 4 divisors (see below), whose sum is σ = 1807488000. Its totient is φ = 1799955844.

The previous prime is 1803721919. The next prime is 1803721967. The reversal of 1803721921 is 1291273081.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1803721921 - 2¹ = 1803721919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1803725921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1882321 + ... + 1883278.

It is an arithmetic number, because the mean of its divisors is an integer number (451872000).

Almost surely, 2^1803721921 is an apocalyptic number.

It is an amenable number.

1803721921 is a deficient number, since it is larger than the sum of its proper divisors (3766079).

1803721921 is an equidigital number, since it uses as much as digits as its factorization.

1803721921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3766078.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 1803721921 is about 42470.2474798535. The cubic root of 1803721921 is about 1217.2782469100.

The spelling of 1803721921 in words is "one billion, eight hundred three million, seven hundred twenty-one thousand, nine hundred twenty-one".