21440317 has 2 divisors, whose sum is σ = 21440318. Its totient is φ = 21440316.

The previous prime is 21440291. The next prime is 21440351. The reversal of 21440317 is 71304412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 151321 = 4614^2 + 389^2 .

It is a cyclic number.

It is not a de Polignac number, because 21440317 - 2¹⁹ = 20916029 is a prime.

It is a plaindrome in base 11.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21440357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720158 + 10720159.

It is an arithmetic number, because the mean of its divisors is an integer number (10720159).

Almost surely, 2^21440317 is an apocalyptic number.

It is an amenable number.

21440317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440317 is an equidigital number, since it uses as much as digits as its factorization.

21440317 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21440317 is about 4630.3689917759. The cubic root of 21440317 is about 277.8073514765.

Adding to 21440317 its reverse (71304412), we get a palindrome (92744729).

The spelling of 21440317 in words is "twenty-one million, four hundred forty thousand, three hundred seventeen".