20305513 has 2 divisors, whose sum is σ = 20305514. Its totient is φ = 20305512.

The previous prime is 20305507. The next prime is 20305517. The reversal of 20305513 is 31550302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20178064 + 127449 = 4492^2 + 357^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20305513 is a prime.

It is not a weakly prime, because it can be changed into another prime (20305517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10152756 + 10152757.

It is an arithmetic number, because the mean of its divisors is an integer number (10152757).

Almost surely, 2^20305513 is an apocalyptic number.

It is an amenable number.

20305513 is a deficient number, since it is larger than the sum of its proper divisors (1).

20305513 is an equidigital number, since it uses as much as digits as its factorization.

20305513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 450, while the sum is 19.

The square root of 20305513 is about 4506.1638896072. The cubic root of 20305513 is about 272.8169328203.

Adding to 20305513 its reverse (31550302), we get a palindrome (51855815).

The spelling of 20305513 in words is "twenty million, three hundred five thousand, five hundred thirteen".