2191721783 has 2 divisors, whose sum is σ = 2191721784. Its totient is φ = 2191721782.

The previous prime is 2191721771. The next prime is 2191721843. The reversal of 2191721783 is 3871271912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2191721783 - 2¹⁰ = 2191720759 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2191721783.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2191721683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095860891 + 1095860892.

It is an arithmetic number, because the mean of its divisors is an integer number (1095860892).

Almost surely, 2^2191721783 is an apocalyptic number.

2191721783 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191721783 is an equidigital number, since it uses as much as digits as its factorization.

2191721783 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 42336, while the sum is 41.

The square root of 2191721783 is about 46815.8283382875. The cubic root of 2191721783 is about 1298.9580967333.

The spelling of 2191721783 in words is "two billion, one hundred ninety-one million, seven hundred twenty-one thousand, seven hundred eighty-three".