1804745021 has 4 divisors (see below), whose sum is σ = 1812838272. Its totient is φ = 1796651772.

The previous prime is 1804744999. The next prime is 1804745051. The reversal of 1804745021 is 1205474081.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1205474081 = 7 ⋅172210583.

It is a cyclic number.

It is not a de Polignac number, because 1804745021 - 2¹⁴ = 1804728637 is a prime.

It is a super-4 number, since 4×1804745021⁴ (a number of 38 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1804745051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4046291 + ... + 4046736.

It is an arithmetic number, because the mean of its divisors is an integer number (453209568).

Almost surely, 2^1804745021 is an apocalyptic number.

It is an amenable number.

1804745021 is a deficient number, since it is larger than the sum of its proper divisors (8093251).

1804745021 is an equidigital number, since it uses as much as digits as its factorization.

1804745021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8093250.

The product of its (nonzero) digits is 8960, while the sum is 32.

The square root of 1804745021 is about 42482.2906750566. The cubic root of 1804745021 is about 1217.5083566559.

The spelling of 1804745021 in words is "one billion, eight hundred four million, seven hundred forty-five thousand, twenty-one".