1668826409 has 2 divisors, whose sum is σ = 1668826410. Its totient is φ = 1668826408.

The previous prime is 1668826391. The next prime is 1668826457. The reversal of 1668826409 is 9046288661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1065043225 + 603783184 = 32635^2 + 24572^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668826409 - 2⁸ = 1668826153 is a prime.

It is not a weakly prime, because it can be changed into another prime (1668826459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834413204 + 834413205.

It is an arithmetic number, because the mean of its divisors is an integer number (834413205).

Almost surely, 2^1668826409 is an apocalyptic number.

It is an amenable number.

1668826409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668826409 is an equidigital number, since it uses as much as digits as its factorization.

1668826409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 995328, while the sum is 50.

The square root of 1668826409 is about 40851.2718161871. The cubic root of 1668826409 is about 1186.1430119777.

The spelling of 1668826409 in words is "one billion, six hundred sixty-eight million, eight hundred twenty-six thousand, four hundred nine".