20657929 has 2 divisors, whose sum is σ = 20657930. Its totient is φ = 20657928.

The previous prime is 20657927. The next prime is 20657983. The reversal of 20657929 is 92975602.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20430400 + 227529 = 4520^2 + 477^2 .

It is a cyclic number.

It is not a de Polignac number, because 20657929 - 2¹ = 20657927 is a prime.

Together with 20657927, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 20657891 and 20657900.

It is not a weakly prime, because it can be changed into another prime (20657927) 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, 10328964 + 10328965.

It is an arithmetic number, because the mean of its divisors is an integer number (10328965).

Almost surely, 2^20657929 is an apocalyptic number.

It is an amenable number.

20657929 is a deficient number, since it is larger than the sum of its proper divisors (1).

20657929 is an equidigital number, since it uses as much as digits as its factorization.

20657929 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 68040, while the sum is 40.

The square root of 20657929 is about 4545.0994488570. The cubic root of 20657929 is about 274.3861968438.

The spelling of 20657929 in words is "twenty million, six hundred fifty-seven thousand, nine hundred twenty-nine".