20490257 has 2 divisors, whose sum is σ = 20490258. Its totient is φ = 20490256.

The previous prime is 20490251. The next prime is 20490271. The reversal of 20490257 is 75209402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12103441 + 8386816 = 3479^2 + 2896^2 .

It is a cyclic number.

It is not a de Polignac number, because 20490257 - 2¹⁶ = 20424721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20490251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10245128 + 10245129.

It is an arithmetic number, because the mean of its divisors is an integer number (10245129).

Almost surely, 2^20490257 is an apocalyptic number.

It is an amenable number.

20490257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20490257 is an equidigital number, since it uses as much as digits as its factorization.

20490257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 20490257 is about 4526.6165068404. The cubic root of 20490257 is about 273.6418189059.

Adding to 20490257 its reverse (75209402), we get a palindrome (95699659).

The spelling of 20490257 in words is "twenty million, four hundred ninety thousand, two hundred fifty-seven".