19658563681 has 9 divisors (see below), whose sum is σ = 19812440473. Its totient is φ = 19505876080.

The previous prime is 19658563679. The next prime is 19658563723. The reversal of 19658563681 is 18636585691.

The square root of 19658563681 is 140209.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1884341281 + 17774222400 = 43409^2 + 133320^2 .

It is not a de Polignac number, because 19658563681 - 2¹ = 19658563679 is a prime.

It is a super-2 number, since 2×19658563681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19658563621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 20890671 + ... + 20891611.

Almost surely, 2^19658563681 is an apocalyptic number.

19658563681 is the 140209-th square number.

19658563681 is the 70105-th centered octagonal number.

It is an amenable number.

19658563681 is a deficient number, since it is larger than the sum of its proper divisors (153876792).

19658563681 is an frugal number, since it uses more digits than its factorization.

19658563681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2180 (or 1090 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 58.

The spelling of 19658563681 in words is "nineteen billion, six hundred fifty-eight million, five hundred sixty-three thousand, six hundred eighty-one".