20315100644561 has 2 divisors, whose sum is σ = 20315100644562. Its totient is φ = 20315100644560.

The previous prime is 20315100644521. The next prime is 20315100644593. The reversal of 20315100644561 is 16544600151302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20313995481025 + 1105163536 = 4507105^2 + 33244^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20315100644561 is a prime.

It is not a weakly prime, because it can be changed into another prime (20315100644521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10157550322280 + 10157550322281.

It is an arithmetic number, because the mean of its divisors is an integer number (10157550322281).

Almost surely, 2^{20315100644561} is an apocalyptic number.

It is an amenable number.

20315100644561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20315100644561 is an equidigital number, since it uses as much as digits as its factorization.

20315100644561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 86400, while the sum is 38.

Adding to 20315100644561 its reverse (16544600151302), we get a palindrome (36859700795863).

The spelling of 20315100644561 in words is "twenty trillion, three hundred fifteen billion, one hundred million, six hundred forty-four thousand, five hundred sixty-one".