21450317 has 12 divisors (see below), whose sum is σ = 24879456. Its totient is φ = 18116280.

The previous prime is 21450313. The next prime is 21450323. The reversal of 21450317 is 71305412.

It is not a de Polignac number, because 21450317 - 2² = 21450313 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21450292 and 21450301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43442 + ... + 43932.

It is an arithmetic number, because the mean of its divisors is an integer number (2073288).

Almost surely, 2^21450317 is an apocalyptic number.

It is an amenable number.

21450317 is a deficient number, since it is larger than the sum of its proper divisors (3429139).

21450317 is an frugal number, since it uses more digits than its factorization.

21450317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656 (or 577 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21450317 is about 4631.4486934436. The cubic root of 21450317 is about 277.8505355662.

Adding to 21450317 its reverse (71305412), we get a palindrome (92755729).

The spelling of 21450317 in words is "twenty-one million, four hundred fifty thousand, three hundred seventeen".