1671449821 has 4 divisors (see below), whose sum is σ = 1673516700. Its totient is φ = 1669382944.

The previous prime is 1671449743. The next prime is 1671449831. The reversal of 1671449821 is 1289441761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1289441761 = 29 ⋅44463509.

It can be written as a sum of positive squares in 2 ways, for example, as 667447225 + 1004002596 = 25835^2 + 31686^2 .

It is a cyclic number.

It is not a de Polignac number, because 1671449821 - 2⁹ = 1671449309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1671449831) 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, 1032226 + ... + 1033843.

It is an arithmetic number, because the mean of its divisors is an integer number (418379175).

Almost surely, 2^1671449821 is an apocalyptic number.

It is an amenable number.

1671449821 is a deficient number, since it is larger than the sum of its proper divisors (2066879).

1671449821 is an equidigital number, since it uses as much as digits as its factorization.

1671449821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2066878.

The product of its digits is 96768, while the sum is 43.

The square root of 1671449821 is about 40883.3685133698. The cubic root of 1671449821 is about 1186.7642295100.

The spelling of 1671449821 in words is "one billion, six hundred seventy-one million, four hundred forty-nine thousand, eight hundred twenty-one".