21113344181 has 2 divisors, whose sum is σ = 21113344182. Its totient is φ = 21113344180.

The previous prime is 21113344177. The next prime is 21113344249. The reversal of 21113344181 is 18144331112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19157051281 + 1956292900 = 138409^2 + 44230^2 .

It is a cyclic number.

It is not a de Polignac number, because 21113344181 - 2² = 21113344177 is a prime.

It is a super-2 number, since 2×21113344181² (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 (21113344781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556672090 + 10556672091.

It is an arithmetic number, because the mean of its divisors is an integer number (10556672091).

Almost surely, 2^21113344181 is an apocalyptic number.

It is an amenable number.

21113344181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21113344181 is an equidigital number, since it uses as much as digits as its factorization.

21113344181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 29.

Adding to 21113344181 its reverse (18144331112), we get a palindrome (39257675293).

The spelling of 21113344181 in words is "twenty-one billion, one hundred thirteen million, three hundred forty-four thousand, one hundred eighty-one".