20013721542161 has 2 divisors, whose sum is σ = 20013721542162. Its totient is φ = 20013721542160.

The previous prime is 20013721542127. The next prime is 20013721542173. The reversal of 20013721542161 is 16124512731002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18364438890625 + 1649282651536 = 4285375^2 + 1284244^2 .

It is a cyclic number.

It is not a de Polignac number, because 20013721542161 - 2²² = 20013717347857 is a prime.

It is a super-2 number, since 2×20013721542161² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20013721542121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10006860771080 + 10006860771081.

It is an arithmetic number, because the mean of its divisors is an integer number (10006860771081).

Almost surely, 2^{20013721542161} is an apocalyptic number.

It is an amenable number.

20013721542161 is a deficient number, since it is larger than the sum of its proper divisors (1).

20013721542161 is an equidigital number, since it uses as much as digits as its factorization.

20013721542161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 35.

The spelling of 20013721542161 in words is "twenty trillion, thirteen billion, seven hundred twenty-one million, five hundred forty-two thousand, one hundred sixty-one".