21404440181 has 2 divisors, whose sum is σ = 21404440182. Its totient is φ = 21404440180.

The previous prime is 21404440073. The next prime is 21404440193. The reversal of 21404440181 is 18104440412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17304087025 + 4100353156 = 131545^2 + 64034^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21404440181 is a prime.

It is a super-2 number, since 2×21404440181² (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 (21404440381) 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, 10702220090 + 10702220091.

It is an arithmetic number, because the mean of its divisors is an integer number (10702220091).

Almost surely, 2^21404440181 is an apocalyptic number.

It is an amenable number.

21404440181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21404440181 is an equidigital number, since it uses as much as digits as its factorization.

21404440181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4096, while the sum is 29.

Adding to 21404440181 its reverse (18104440412), we get a palindrome (39508880593).

The spelling of 21404440181 in words is "twenty-one billion, four hundred four million, four hundred forty thousand, one hundred eighty-one".