20115817 has 2 divisors, whose sum is σ = 20115818. Its totient is φ = 20115816.

The previous prime is 20115803. The next prime is 20115829. The reversal of 20115817 is 71851102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19900521 + 215296 = 4461^2 + 464^2 .

It is a cyclic number.

It is not a de Polignac number, because 20115817 - 2¹⁹ = 19591529 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20115791 and 20115800.

It is not a weakly prime, because it can be changed into another prime (20115917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10057908 + 10057909.

It is an arithmetic number, because the mean of its divisors is an integer number (10057909).

Almost surely, 2^20115817 is an apocalyptic number.

It is an amenable number.

20115817 is a deficient number, since it is larger than the sum of its proper divisors (1).

20115817 is an equidigital number, since it uses as much as digits as its factorization.

20115817 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 560, while the sum is 25.

The square root of 20115817 is about 4485.0659972848. The cubic root of 20115817 is about 271.9647130190.

Adding to 20115817 its reverse (71851102), we get a palindrome (91966919).

The spelling of 20115817 in words is "twenty million, one hundred fifteen thousand, eight hundred seventeen".