21286317 has 16 divisors (see below), whose sum is σ = 30648128. Its totient is φ = 13063680.

The previous prime is 21286303. The next prime is 21286351. The reversal of 21286317 is 71368212.

It is not a de Polignac number, because 21286317 - 2⁴ = 21286301 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 (21286357) 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, 25842 + ... + 26652.

It is an arithmetic number, because the mean of its divisors is an integer number (1915508).

Almost surely, 2^21286317 is an apocalyptic number.

It is an amenable number.

21286317 is a deficient number, since it is larger than the sum of its proper divisors (9361811).

21286317 is a wasteful number, since it uses less digits than its factorization.

21286317 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1500.

The product of its digits is 4032, while the sum is 30.

The square root of 21286317 is about 4613.7096787726. The cubic root of 21286317 is about 277.1406142240.

The spelling of 21286317 in words is "twenty-one million, two hundred eighty-six thousand, three hundred seventeen".