20910257 has 2 divisors, whose sum is σ = 20910258. Its totient is φ = 20910256.

The previous prime is 20910179. The next prime is 20910259. The reversal of 20910257 is 75201902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16313521 + 4596736 = 4039^2 + 2144^2 .

It is a cyclic number.

It is not a de Polignac number, because 20910257 - 2¹⁶ = 20844721 is a prime.

Together with 20910259, 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 (20910259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10455128 + 10455129.

It is an arithmetic number, because the mean of its divisors is an integer number (10455129).

Almost surely, 2^20910257 is an apocalyptic number.

It is an amenable number.

20910257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20910257 is an equidigital number, since it uses as much as digits as its factorization.

20910257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 20910257 is about 4572.7734472637. The cubic root of 20910257 is about 275.4988499112.

The spelling of 20910257 in words is "twenty million, nine hundred ten thousand, two hundred fifty-seven".