20702257 has 2 divisors, whose sum is σ = 20702258. Its totient is φ = 20702256.

The previous prime is 20702239. The next prime is 20702281. The reversal of 20702257 is 75220702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10817521 + 9884736 = 3289^2 + 3144^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20702257 is a prime.

It is not a weakly prime, because it can be changed into another prime (20702057) 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, 10351128 + 10351129.

It is an arithmetic number, because the mean of its divisors is an integer number (10351129).

Almost surely, 2^20702257 is an apocalyptic number.

It is an amenable number.

20702257 is a deficient number, since it is larger than the sum of its proper divisors (1).

20702257 is an equidigital number, since it uses as much as digits as its factorization.

20702257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1960, while the sum is 25.

The square root of 20702257 is about 4549.9732966249. The cubic root of 20702257 is about 274.5823168883.

Adding to 20702257 its reverse (75220702), we get a palindrome (95922959).

The spelling of 20702257 in words is "twenty million, seven hundred two thousand, two hundred fifty-seven".