20205281 has 2 divisors, whose sum is σ = 20205282. Its totient is φ = 20205280.

The previous prime is 20205259. The next prime is 20205287. The reversal of 20205281 is 18250202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20205025 + 256 = 4495^2 + 16^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20205281 is a prime.

It is a super-2 number, since 2×20205281² = 816506760577922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20205287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10102640 + 10102641.

It is an arithmetic number, because the mean of its divisors is an integer number (10102641).

Almost surely, 2^20205281 is an apocalyptic number.

It is an amenable number.

20205281 is a deficient number, since it is larger than the sum of its proper divisors (1).

20205281 is an equidigital number, since it uses as much as digits as its factorization.

20205281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 20205281 is about 4495.0284759943. The cubic root of 20205281 is about 272.3672995276.

Adding to 20205281 its reverse (18250202), we get a palindrome (38455483).

The spelling of 20205281 in words is "twenty million, two hundred five thousand, two hundred eighty-one".