20857313 has 2 divisors, whose sum is σ = 20857314. Its totient is φ = 20857312.

The previous prime is 20857247. The next prime is 20857321. The reversal of 20857313 is 31375802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11444689 + 9412624 = 3383^2 + 3068^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20857313 is a prime.

It is not a weakly prime, because it can be changed into another prime (20857373) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428656 + 10428657.

It is an arithmetic number, because the mean of its divisors is an integer number (10428657).

Almost surely, 2^20857313 is an apocalyptic number.

It is an amenable number.

20857313 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857313 is an equidigital number, since it uses as much as digits as its factorization.

20857313 is an evil number, because the sum of its binary digits is even.

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

The square root of 20857313 is about 4566.9807312928. The cubic root of 20857313 is about 275.2661357481.

The spelling of 20857313 in words is "twenty million, eight hundred fifty-seven thousand, three hundred thirteen".