20451257 has 2 divisors, whose sum is σ = 20451258. Its totient is φ = 20451256.

The previous prime is 20451253. The next prime is 20451259. The reversal of 20451257 is 75215402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19149376 + 1301881 = 4376^2 + 1141^2 .

It is a cyclic number.

It is not a de Polignac number, because 20451257 - 2² = 20451253 is a prime.

Together with 20451259, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20451253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10225628 + 10225629.

It is an arithmetic number, because the mean of its divisors is an integer number (10225629).

Almost surely, 2^20451257 is an apocalyptic number.

It is an amenable number.

20451257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20451257 is an equidigital number, since it uses as much as digits as its factorization.

20451257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 20451257 is about 4522.3066017244. The cubic root of 20451257 is about 273.4680971715.

Adding to 20451257 its reverse (75215402), we get a palindrome (95666659).

The spelling of 20451257 in words is "twenty million, four hundred fifty-one thousand, two hundred fifty-seven".