19857355517 has 2 divisors, whose sum is σ = 19857355518. Its totient is φ = 19857355516.

The previous prime is 19857355493. The next prime is 19857355603. The reversal of 19857355517 is 71555375891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9973217956 + 9884137561 = 99866^2 + 99419^2 .

It is an emirp because it is prime and its reverse (71555375891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19857355517 - 2²⁰ = 19856306941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19857352517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9928677758 + 9928677759.

It is an arithmetic number, because the mean of its divisors is an integer number (9928677759).

Almost surely, 2^19857355517 is an apocalyptic number.

It is an amenable number.

19857355517 is a deficient number, since it is larger than the sum of its proper divisors (1).

19857355517 is an equidigital number, since it uses as much as digits as its factorization.

19857355517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6615000, while the sum is 56.

The spelling of 19857355517 in words is "nineteen billion, eight hundred fifty-seven million, three hundred fifty-five thousand, five hundred seventeen".