136643601221 has 2 divisors, whose sum is σ = 136643601222. Its totient is φ = 136643601220.

The previous prime is 136643601209. The next prime is 136643601293. The reversal of 136643601221 is 122106346631.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 86192152225 + 50451448996 = 293585^2 + 224614^2 .

It is a cyclic number.

It is not a de Polignac number, because 136643601221 - 2²⁶ = 136576492357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (136643661221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68321800610 + 68321800611.

It is an arithmetic number, because the mean of its divisors is an integer number (68321800611).

Almost surely, 2^136643601221 is an apocalyptic number.

It is an amenable number.

136643601221 is a deficient number, since it is larger than the sum of its proper divisors (1).

136643601221 is an equidigital number, since it uses as much as digits as its factorization.

136643601221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 35.

Adding to 136643601221 its reverse (122106346631), we get a palindrome (258749947852).

The spelling of 136643601221 in words is "one hundred thirty-six billion, six hundred forty-three million, six hundred one thousand, two hundred twenty-one".