221708086137691 has 2 divisors, whose sum is σ = 221708086137692. Its totient is φ = 221708086137690.

The previous prime is 221708086137679. The next prime is 221708086137697. The reversal of 221708086137691 is 196731680807122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221708086137691 - 2¹¹ = 221708086135643 is a prime.

It is a super-2 number, since 2×221708086137691² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221708086137697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110854043068845 + 110854043068846.

It is an arithmetic number, because the mean of its divisors is an integer number (110854043068846).

Almost surely, 2^{221708086137691} is an apocalyptic number.

221708086137691 is a deficient number, since it is larger than the sum of its proper divisors (1).

221708086137691 is an equidigital number, since it uses as much as digits as its factorization.

221708086137691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12192768, while the sum is 61.

The spelling of 221708086137691 in words is "two hundred twenty-one trillion, seven hundred eight billion, eighty-six million, one hundred thirty-seven thousand, six hundred ninety-one".