1199021891 has 2 divisors, whose sum is σ = 1199021892. Its totient is φ = 1199021890.

The previous prime is 1199021881. The next prime is 1199021911. The reversal of 1199021891 is 1981209911.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1199021891 is a prime.

It is not a weakly prime, because it can be changed into another prime (1199021851) 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, 599510945 + 599510946.

It is an arithmetic number, because the mean of its divisors is an integer number (599510946).

Almost surely, 2^1199021891 is an apocalyptic number.

1199021891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1199021891 is an equidigital number, since it uses as much as digits as its factorization.

1199021891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 41.

The square root of 1199021891 is about 34626.8954860236. The cubic root of 1199021891 is about 1062.3697696162.

The spelling of 1199021891 in words is "one billion, one hundred ninety-nine million, twenty-one thousand, eight hundred ninety-one".