20660251 has 2 divisors, whose sum is σ = 20660252. Its totient is φ = 20660250.

The previous prime is 20660243. The next prime is 20660261. The reversal of 20660251 is 15206602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20660251 - 2³ = 20660243 is a prime.

It is not a weakly prime, because it can be changed into another prime (20660231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10330125 + 10330126.

It is an arithmetic number, because the mean of its divisors is an integer number (10330126).

Almost surely, 2^20660251 is an apocalyptic number.

20660251 is a deficient number, since it is larger than the sum of its proper divisors (1).

20660251 is an equidigital number, since it uses as much as digits as its factorization.

20660251 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 20660251 is about 4545.3548816347. The cubic root of 20660251 is about 274.3964770108.

Adding to 20660251 its reverse (15206602), we get a palindrome (35866853).

The spelling of 20660251 in words is "twenty million, six hundred sixty thousand, two hundred fifty-one".