21702517 has 2 divisors, whose sum is σ = 21702518. Its totient is φ = 21702516.

The previous prime is 21702491. The next prime is 21702529. The reversal of 21702517 is 71520712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12666481 + 9036036 = 3559^2 + 3006^2 .

It is a cyclic number.

It is not a de Polignac number, because 21702517 - 2¹⁹ = 21178229 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21702491 and 21702500.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21702587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10851258 + 10851259.

It is an arithmetic number, because the mean of its divisors is an integer number (10851259).

Almost surely, 2^21702517 is an apocalyptic number.

It is an amenable number.

21702517 is a deficient number, since it is larger than the sum of its proper divisors (1).

21702517 is an equidigital number, since it uses as much as digits as its factorization.

21702517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21702517 is about 4658.5960331413. The cubic root of 21702517 is about 278.9352290302.

The spelling of 21702517 in words is "twenty-one million, seven hundred two thousand, five hundred seventeen".