20957689 has 2 divisors, whose sum is σ = 20957690. Its totient is φ = 20957688.

The previous prime is 20957663. The next prime is 20957707. The reversal of 20957689 is 98675902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20548089 + 409600 = 4533^2 + 640^2 .

It is a cyclic number.

It is not a de Polignac number, because 20957689 - 2⁷ = 20957561 is a prime.

It is not a weakly prime, because it can be changed into another prime (20957609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10478844 + 10478845.

It is an arithmetic number, because the mean of its divisors is an integer number (10478845).

Almost surely, 2^20957689 is an apocalyptic number.

It is an amenable number.

20957689 is a deficient number, since it is larger than the sum of its proper divisors (1).

20957689 is an equidigital number, since it uses as much as digits as its factorization.

20957689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 272160, while the sum is 46.

The square root of 20957689 is about 4577.9568586871. The cubic root of 20957689 is about 275.7070028336.

The spelling of 20957689 in words is "twenty million, nine hundred fifty-seven thousand, six hundred eighty-nine".