136561640021 has 2 divisors, whose sum is σ = 136561640022. Its totient is φ = 136561640020.

The previous prime is 136561639997. The next prime is 136561640027. The reversal of 136561640021 is 120046165631.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134018959396 + 2542680625 = 366086^2 + 50425^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-136561640021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (136561640027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68280820010 + 68280820011.

It is an arithmetic number, because the mean of its divisors is an integer number (68280820011).

Almost surely, 2^136561640021 is an apocalyptic number.

It is an amenable number.

136561640021 is a deficient number, since it is larger than the sum of its proper divisors (1).

136561640021 is an equidigital number, since it uses as much as digits as its factorization.

136561640021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 35.

The spelling of 136561640021 in words is "one hundred thirty-six billion, five hundred sixty-one million, six hundred forty thousand, twenty-one".