196658806491821 has 2 divisors, whose sum is σ = 196658806491822. Its totient is φ = 196658806491820.

The previous prime is 196658806491743. The next prime is 196658806491841. The reversal of 196658806491821 is 128194608856691.

196658806491821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 103819511342596 + 92839295149225 = 10189186^2 + 9635315^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-196658806491821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (196658806491841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98329403245910 + 98329403245911.

It is an arithmetic number, because the mean of its divisors is an integer number (98329403245911).

Almost surely, 2^{196658806491821} is an apocalyptic number.

It is an amenable number.

196658806491821 is a deficient number, since it is larger than the sum of its proper divisors (1).

196658806491821 is an equidigital number, since it uses as much as digits as its factorization.

196658806491821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 358318080, while the sum is 74.

The spelling of 196658806491821 in words is "one hundred ninety-six trillion, six hundred fifty-eight billion, eight hundred six million, four hundred ninety-one thousand, eight hundred twenty-one".