19678500581 has 2 divisors, whose sum is σ = 19678500582. Its totient is φ = 19678500580.

The previous prime is 19678500577. The next prime is 19678500601. The reversal of 19678500581 is 18500587691.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18668849956 + 1009650625 = 136634^2 + 31775^2 .

It is a cyclic number.

It is not a de Polignac number, because 19678500581 - 2² = 19678500577 is a prime.

It is a super-2 number, since 2×19678500581² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19678500781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9839250290 + 9839250291.

It is an arithmetic number, because the mean of its divisors is an integer number (9839250291).

Almost surely, 2^19678500581 is an apocalyptic number.

It is an amenable number.

19678500581 is a deficient number, since it is larger than the sum of its proper divisors (1).

19678500581 is an equidigital number, since it uses as much as digits as its factorization.

19678500581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 604800, while the sum is 50.

The spelling of 19678500581 in words is "nineteen billion, six hundred seventy-eight million, five hundred thousand, five hundred eighty-one".