21420001181 has 2 divisors, whose sum is σ = 21420001182. Its totient is φ = 21420001180.

The previous prime is 21420001159. The next prime is 21420001247. The reversal of 21420001181 is 18110002412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18822468025 + 2597533156 = 137195^2 + 50966^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420001181 - 2⁶ = 21420001117 is a prime.

It is a super-2 number, since 2×21420001181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21420001151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710000590 + 10710000591.

It is an arithmetic number, because the mean of its divisors is an integer number (10710000591).

Almost surely, 2^21420001181 is an apocalyptic number.

It is an amenable number.

21420001181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420001181 is an equidigital number, since it uses as much as digits as its factorization.

21420001181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21420001181 its reverse (18110002412), we get a palindrome (39530003593).

The spelling of 21420001181 in words is "twenty-one billion, four hundred twenty million, one thousand, one hundred eighty-one".