1668191951 has 2 divisors, whose sum is σ = 1668191952. Its totient is φ = 1668191950.

The previous prime is 1668191947. The next prime is 1668191957. The reversal of 1668191951 is 1591918661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1668191951 - 2² = 1668191947 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1668191896 and 1668191905.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1668191957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834095975 + 834095976.

It is an arithmetic number, because the mean of its divisors is an integer number (834095976).

Almost surely, 2^1668191951 is an apocalyptic number.

1668191951 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668191951 is an equidigital number, since it uses as much as digits as its factorization.

1668191951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 47.

The square root of 1668191951 is about 40843.5056159483. The cubic root of 1668191951 is about 1185.9926761271.

The spelling of 1668191951 in words is "one billion, six hundred sixty-eight million, one hundred ninety-one thousand, nine hundred fifty-one".