20857680497 has 2 divisors, whose sum is σ = 20857680498. Its totient is φ = 20857680496.

The previous prime is 20857680463. The next prime is 20857680551. The reversal of 20857680497 is 79408675802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12874079296 + 7983601201 = 113464^2 + 89351^2 .

It is a cyclic number.

It is not a de Polignac number, because 20857680497 - 2¹⁶ = 20857614961 is a prime.

It is not a weakly prime, because it can be changed into another prime (20857680097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428840248 + 10428840249.

It is an arithmetic number, because the mean of its divisors is an integer number (10428840249).

Almost surely, 2^20857680497 is an apocalyptic number.

It is an amenable number.

20857680497 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857680497 is an equidigital number, since it uses as much as digits as its factorization.

20857680497 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6773760, while the sum is 56.

The spelling of 20857680497 in words is "twenty billion, eight hundred fifty-seven million, six hundred eighty thousand, four hundred ninety-seven".