2191721699 has 2 divisors, whose sum is σ = 2191721700. Its totient is φ = 2191721698.

The previous prime is 2191721683. The next prime is 2191721711. The reversal of 2191721699 is 9961271912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2191721699 - 2⁴ = 2191721683 is a prime.

It is not a weakly prime, because it can be changed into another prime (2191721639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1095860849 + 1095860850.

It is an arithmetic number, because the mean of its divisors is an integer number (1095860850).

Almost surely, 2^2191721699 is an apocalyptic number.

2191721699 is a deficient number, since it is larger than the sum of its proper divisors (1).

2191721699 is an equidigital number, since it uses as much as digits as its factorization.

2191721699 is an evil number, because the sum of its binary digits is even.

The product of its digits is 122472, while the sum is 47.

The square root of 2191721699 is about 46815.8274411550. The cubic root of 2191721699 is about 1298.9580801386.

The spelling of 2191721699 in words is "two billion, one hundred ninety-one million, seven hundred twenty-one thousand, six hundred ninety-nine".