21404317 has 16 divisors (see below), whose sum is σ = 25113600. Its totient is φ = 18033840.

The previous prime is 21404303. The next prime is 21404321. The reversal of 21404317 is 71340412.

It is a de Polignac number, because none of the positive numbers 2^k-21404317 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404017) 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 15 ways as a sum of consecutive naturals, for example, 8734 + ... + 10912.

It is an arithmetic number, because the mean of its divisors is an integer number (1569600).

Almost surely, 2^21404317 is an apocalyptic number.

It is an amenable number.

21404317 is a deficient number, since it is larger than the sum of its proper divisors (3709283).

21404317 is a wasteful number, since it uses less digits than its factorization.

21404317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2256.

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

The square root of 21404317 is about 4626.4799794228. The cubic root of 21404317 is about 277.6517774800.

Adding to 21404317 its reverse (71340412), we get a palindrome (92744729).

The spelling of 21404317 in words is "twenty-one million, four hundred four thousand, three hundred seventeen".