19519163521 has 27 divisors (see below), whose sum is σ = 23256084873. Its totient is φ = 16362952320.

The previous prime is 19519163491. The next prime is 19519163537. The reversal of 19519163521 is 12536191591.

The square root of 19519163521 is 139711.

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 370139121 + 19149024400 = 19239^2 + 138380^2 .

It is not a de Polignac number, because 19519163521 - 2⁹ = 19519163009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19519113521) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 19978185 + ... + 19979161.

Almost surely, 2^19519163521 is an apocalyptic number.

19519163521 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

19519163521 is the 139711-st square number.

19519163521 is the 69856-th centered octagonal number.

It is an amenable number.

19519163521 is a deficient number, since it is larger than the sum of its proper divisors (3736921352).

19519163521 is an frugal number, since it uses more digits than its factorization.

19519163521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2002 (or 1001 counting only the distinct ones).

The product of its digits is 72900, while the sum is 43.

The spelling of 19519163521 in words is "nineteen billion, five hundred nineteen million, one hundred sixty-three thousand, five hundred twenty-one".