21584317 has 2 divisors, whose sum is σ = 21584318. Its totient is φ = 21584316.

The previous prime is 21584309. The next prime is 21584347. The reversal of 21584317 is 71348512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19307236 + 2277081 = 4394^2 + 1509^2 .

It is a cyclic number.

It is not a de Polignac number, because 21584317 - 2³ = 21584309 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21584347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10792158 + 10792159.

It is an arithmetic number, because the mean of its divisors is an integer number (10792159).

Almost surely, 2^21584317 is an apocalyptic number.

It is an amenable number.

21584317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21584317 is an equidigital number, since it uses as much as digits as its factorization.

21584317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 31.

The square root of 21584317 is about 4645.8924869179. The cubic root of 21584317 is about 278.4279118107.

It can be divided in two parts, 2158 and 4317, that multiplied together give a triangular number (9316086 = T₄₃₁₆).

The spelling of 21584317 in words is "twenty-one million, five hundred eighty-four thousand, three hundred seventeen".