1668839021 has 2 divisors, whose sum is σ = 1668839022. Its totient is φ = 1668839020.

The previous prime is 1668838979. The next prime is 1668839041. The reversal of 1668839021 is 1209388661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1572994921 + 95844100 = 39661^2 + 9790^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668839021 - 2⁶ = 1668838957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1668839041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834419510 + 834419511.

It is an arithmetic number, because the mean of its divisors is an integer number (834419511).

Almost surely, 2^1668839021 is an apocalyptic number.

It is an amenable number.

1668839021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668839021 is an equidigital number, since it uses as much as digits as its factorization.

1668839021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 124416, while the sum is 44.

The square root of 1668839021 is about 40851.4261807345. The cubic root of 1668839021 is about 1186.1460000252.

The spelling of 1668839021 in words is "one billion, six hundred sixty-eight million, eight hundred thirty-nine thousand, twenty-one".