21432412181 has 2 divisors, whose sum is σ = 21432412182. Its totient is φ = 21432412180.

The previous prime is 21432412109. The next prime is 21432412187. The reversal of 21432412181 is 18121423412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18826309681 + 2606102500 = 137209^2 + 51050^2 .

It is a cyclic number.

It is not a de Polignac number, because 21432412181 - 2¹⁰ = 21432411157 is a prime.

It is a super-2 number, since 2×21432412181² (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 (21432412187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10716206090 + 10716206091.

It is an arithmetic number, because the mean of its divisors is an integer number (10716206091).

Almost surely, 2^21432412181 is an apocalyptic number.

It is an amenable number.

21432412181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21432412181 is an equidigital number, since it uses as much as digits as its factorization.

21432412181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3072, while the sum is 29.

Adding to 21432412181 its reverse (18121423412), we get a palindrome (39553835593).

The spelling of 21432412181 in words is "twenty-one billion, four hundred thirty-two million, four hundred twelve thousand, one hundred eighty-one".