20013250421561 has 2 divisors, whose sum is σ = 20013250421562. Its totient is φ = 20013250421560.

The previous prime is 20013250421551. The next prime is 20013250421569. The reversal of 20013250421561 is 16512405231002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19437905416336 + 575345005225 = 4408844^2 + 758515^2 .

It is a cyclic number.

It is not a de Polignac number, because 20013250421561 - 2²⁶ = 20013183312697 is a prime.

It is a super-2 number, since 2×20013250421561² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20013250421569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10006625210780 + 10006625210781.

It is an arithmetic number, because the mean of its divisors is an integer number (10006625210781).

Almost surely, 2^{20013250421561} is an apocalyptic number.

It is an amenable number.

20013250421561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20013250421561 is an equidigital number, since it uses as much as digits as its factorization.

20013250421561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14400, while the sum is 32.

Adding to 20013250421561 its reverse (16512405231002), we get a palindrome (36525655652563).

The spelling of 20013250421561 in words is "twenty trillion, thirteen billion, two hundred fifty million, four hundred twenty-one thousand, five hundred sixty-one".