21726317 has 2 divisors, whose sum is σ = 21726318. Its totient is φ = 21726316.

The previous prime is 21726311. The next prime is 21726349. The reversal of 21726317 is 71362712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18139081 + 3587236 = 4259^2 + 1894^2 .

It is a cyclic number.

It is not a de Polignac number, because 21726317 - 2¹⁰ = 21725293 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21726317.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21726311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10863158 + 10863159.

It is an arithmetic number, because the mean of its divisors is an integer number (10863159).

Almost surely, 2^21726317 is an apocalyptic number.

It is an amenable number.

21726317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21726317 is an equidigital number, since it uses as much as digits as its factorization.

21726317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3528, while the sum is 29.

The square root of 21726317 is about 4661.1497508662. The cubic root of 21726317 is about 279.0371562732.

The spelling of 21726317 in words is "twenty-one million, seven hundred twenty-six thousand, three hundred seventeen".