21294517 has 2 divisors, whose sum is σ = 21294518. Its totient is φ = 21294516.

The previous prime is 21294491. The next prime is 21294541. The reversal of 21294517 is 71549212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21169201 + 125316 = 4601^2 + 354^2 .

It is a cyclic number.

It is not a de Polignac number, because 21294517 - 2¹⁹ = 20770229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21294577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10647258 + 10647259.

It is an arithmetic number, because the mean of its divisors is an integer number (10647259).

Almost surely, 2^21294517 is an apocalyptic number.

It is an amenable number.

21294517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21294517 is an equidigital number, since it uses as much as digits as its factorization.

21294517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 31.

The square root of 21294517 is about 4614.5982490353. The cubic root of 21294517 is about 277.1761967266.

The spelling of 21294517 in words is "twenty-one million, two hundred ninety-four thousand, five hundred seventeen".