20720417 has 2 divisors, whose sum is σ = 20720418. Its totient is φ = 20720416.

The previous prime is 20720363. The next prime is 20720423. The reversal of 20720417 is 71402702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16072081 + 4648336 = 4009^2 + 2156^2 .

It is a cyclic number.

It is not a de Polignac number, because 20720417 - 2²² = 16526113 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20720392 and 20720401.

It is not a weakly prime, because it can be changed into another prime (20720437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10360208 + 10360209.

It is an arithmetic number, because the mean of its divisors is an integer number (10360209).

Almost surely, 2^20720417 is an apocalyptic number.

It is an amenable number.

20720417 is a deficient number, since it is larger than the sum of its proper divisors (1).

20720417 is an equidigital number, since it uses as much as digits as its factorization.

20720417 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 784, while the sum is 23.

The square root of 20720417 is about 4551.9684752863. The cubic root of 20720417 is about 274.6625812054.

The spelling of 20720417 in words is "twenty million, seven hundred twenty thousand, four hundred seventeen".