209861427197 has 2 divisors, whose sum is σ = 209861427198. Its totient is φ = 209861427196.

The previous prime is 209861427163. The next prime is 209861427221. The reversal of 209861427197 is 791724168902.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 189250230841 + 20611196356 = 435029^2 + 143566^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209861427197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209861427697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104930713598 + 104930713599.

It is an arithmetic number, because the mean of its divisors is an integer number (104930713599).

Almost surely, 2^209861427197 is an apocalyptic number.

It is an amenable number.

209861427197 is a deficient number, since it is larger than the sum of its proper divisors (1).

209861427197 is an equidigital number, since it uses as much as digits as its factorization.

209861427197 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3048192, while the sum is 56.

The spelling of 209861427197 in words is "two hundred nine billion, eight hundred sixty-one million, four hundred twenty-seven thousand, one hundred ninety-seven".