1671647891 has 4 divisors (see below), whose sum is σ = 1672026912. Its totient is φ = 1671268872.

The previous prime is 1671647881. The next prime is 1671647897. The reversal of 1671647891 is 1987461761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1987461761 = 16451 ⋅120811.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1671647891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1671647897) 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, 182816 + ... + 191741.

It is an arithmetic number, because the mean of its divisors is an integer number (418006728).

Almost surely, 2^1671647891 is an apocalyptic number.

1671647891 is a deficient number, since it is larger than the sum of its proper divisors (379021).

1671647891 is an equidigital number, since it uses as much as digits as its factorization.

1671647891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 379020.

The product of its digits is 508032, while the sum is 50.

The square root of 1671647891 is about 40885.7908202838. The cubic root of 1671647891 is about 1186.8111056019.

The spelling of 1671647891 in words is "one billion, six hundred seventy-one million, six hundred forty-seven thousand, eight hundred ninety-one".