20617321 has 2 divisors, whose sum is σ = 20617322. Its totient is φ = 20617320.

The previous prime is 20617313. The next prime is 20617327. The reversal of 20617321 is 12371602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20575296 + 42025 = 4536^2 + 205^2 .

It is a cyclic number.

It is not a de Polignac number, because 20617321 - 2³ = 20617313 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20617292 and 20617301.

It is not a weakly prime, because it can be changed into another prime (20617327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10308660 + 10308661.

It is an arithmetic number, because the mean of its divisors is an integer number (10308661).

Almost surely, 2^20617321 is an apocalyptic number.

It is an amenable number.

20617321 is a deficient number, since it is larger than the sum of its proper divisors (1).

20617321 is an equidigital number, since it uses as much as digits as its factorization.

20617321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 20617321 is about 4540.6300223647. The cubic root of 20617321 is about 274.2062887872.

Adding to 20617321 its reverse (12371602), we get a palindrome (32988923).

The spelling of 20617321 in words is "twenty million, six hundred seventeen thousand, three hundred twenty-one".