20858720417 has 2 divisors, whose sum is σ = 20858720418. Its totient is φ = 20858720416.

The previous prime is 20858720329. The next prime is 20858720423. The reversal of 20858720417 is 71402785802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17436938401 + 3421782016 = 132049^2 + 58496^2 .

It is a cyclic number.

It is not a de Polignac number, because 20858720417 - 2¹⁸ = 20858458273 is a prime.

It is not a weakly prime, because it can be changed into another prime (20858720497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10429360208 + 10429360209.

It is an arithmetic number, because the mean of its divisors is an integer number (10429360209).

Almost surely, 2^20858720417 is an apocalyptic number.

It is an amenable number.

20858720417 is a deficient number, since it is larger than the sum of its proper divisors (1).

20858720417 is an equidigital number, since it uses as much as digits as its factorization.

20858720417 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 250880, while the sum is 44.

The spelling of 20858720417 in words is "twenty billion, eight hundred fifty-eight million, seven hundred twenty thousand, four hundred seventeen".