1668591121 has 4 divisors (see below), whose sum is σ = 1668703744. Its totient is φ = 1668478500.

The previous prime is 1668591107. The next prime is 1668591131. The reversal of 1668591121 is 1211958661.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1211958661 = 26263 ⋅46147.

It is a cyclic number.

It is not a de Polignac number, because 1668591121 - 2¹⁷ = 1668460049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1668591131) 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, 29985 + ... + 65086.

It is an arithmetic number, because the mean of its divisors is an integer number (417175936).

Almost surely, 2^1668591121 is an apocalyptic number.

It is an amenable number.

1668591121 is a deficient number, since it is larger than the sum of its proper divisors (112623).

1668591121 is an equidigital number, since it uses as much as digits as its factorization.

1668591121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112622.

The product of its digits is 25920, while the sum is 40.

The square root of 1668591121 is about 40848.3919022524. The cubic root of 1668591121 is about 1186.0872645509.

The spelling of 1668591121 in words is "one billion, six hundred sixty-eight million, five hundred ninety-one thousand, one hundred twenty-one".