2191865321 has 2 divisors, whose sum is σ = 2191865322. Its totient is φ = 2191865320.

The previous prime is 2191865309. The next prime is 2191865383. The reversal of 2191865321 is 1235681912.

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., 2121892096 + 69973225 = 46064^2 + 8365^2 .

It is a cyclic number.

It is not a de Polignac number, because 2191865321 - 2²⁶ = 2124756457 is a prime.

It is not a weakly prime, because it can be changed into another prime (2191865521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095932660 + 1095932661.

It is an arithmetic number, because the mean of its divisors is an integer number (1095932661).

Almost surely, 2^2191865321 is an apocalyptic number.

It is an amenable number.

2191865321 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191865321 is an equidigital number, since it uses as much as digits as its factorization.

2191865321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 38.

The square root of 2191865321 is about 46817.3613203478. The cubic root of 2191865321 is about 1298.9864527924.

The spelling of 2191865321 in words is "two billion, one hundred ninety-one million, eight hundred sixty-five thousand, three hundred twenty-one".