21168481 has 2 divisors, whose sum is σ = 21168482. Its totient is φ = 21168480.

The previous prime is 21168479. The next prime is 21168491. The reversal of 21168481 is 18486112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15210000 + 5958481 = 3900^2 + 2441^2 .

It is a cyclic number.

It is not a de Polignac number, because 21168481 - 2¹ = 21168479 is a prime.

It is a super-2 number, since 2×21168481² = 896209175694722, which contains 22 as substring.

Together with 21168479, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21168461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10584240 + 10584241.

It is an arithmetic number, because the mean of its divisors is an integer number (10584241).

Almost surely, 2^21168481 is an apocalyptic number.

It is an amenable number.

21168481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21168481 is an equidigital number, since it uses as much as digits as its factorization.

21168481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3072, while the sum is 31.

The square root of 21168481 is about 4600.9217554747. The cubic root of 21168481 is about 276.6282727645.

The spelling of 21168481 in words is "twenty-one million, one hundred sixty-eight thousand, four hundred eighty-one".