20118521 has 2 divisors, whose sum is σ = 20118522. Its totient is φ = 20118520.

The previous prime is 20118517. The next prime is 20118523. The reversal of 20118521 is 12581102.

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., 12075625 + 8042896 = 3475^2 + 2836^2 .

It is a cyclic number.

It is not a de Polignac number, because 20118521 - 2² = 20118517 is a prime.

Together with 20118523, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20118493 and 20118502.

It is not a weakly prime, because it can be changed into another prime (20118523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10059260 + 10059261.

It is an arithmetic number, because the mean of its divisors is an integer number (10059261).

Almost surely, 2^20118521 is an apocalyptic number.

It is an amenable number.

20118521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20118521 is an equidigital number, since it uses as much as digits as its factorization.

20118521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 20118521 is about 4485.3674319948. The cubic root of 20118521 is about 271.9768984489.

Adding to 20118521 its reverse (12581102), we get a palindrome (32699623).

The spelling of 20118521 in words is "twenty million, one hundred eighteen thousand, five hundred twenty-one".