1667128891 has 2 divisors, whose sum is σ = 1667128892. Its totient is φ = 1667128890.

The previous prime is 1667128871. The next prime is 1667128901. The reversal of 1667128891 is 1988217661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1667128891 - 2¹³ = 1667120699 is a prime.

It is not a weakly prime, because it can be changed into another prime (1667128811) 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, 833564445 + 833564446.

It is an arithmetic number, because the mean of its divisors is an integer number (833564446).

Almost surely, 2^1667128891 is an apocalyptic number.

1667128891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1667128891 is an equidigital number, since it uses as much as digits as its factorization.

1667128891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 290304, while the sum is 49.

The square root of 1667128891 is about 40830.4897227550. The cubic root of 1667128891 is about 1185.7406968749.

The spelling of 1667128891 in words is "one billion, six hundred sixty-seven million, one hundred twenty-eight thousand, eight hundred ninety-one".