19681003521 has 27 divisors (see below), whose sum is σ = 28774517187. Its totient is φ = 12962703600.

The previous prime is 19681003501. The next prime is 19681003523. The reversal of 19681003521 is 12530018691.

The square root of 19681003521 is 140289.

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

It can be written as a sum of positive squares in only one way, i.e., 18909275121 + 771728400 = 137511^2 + 27780^2 .

It is not a de Polignac number, because 19681003521 - 2²⁵ = 19647449089 is a prime.

It is a super-2 number, since 2×19681003521² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (19681003523) 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, 42507336 + ... + 42507798.

Almost surely, 2^19681003521 is an apocalyptic number.

19681003521 is the 140289-th square number.

19681003521 is the 70145-th centered octagonal number.

It is an amenable number.

19681003521 is a deficient number, since it is larger than the sum of its proper divisors (9093513666).

19681003521 is an frugal number, since it uses more digits than its factorization.

19681003521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1134 (or 567 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

Multiplying 19681003521 by its sum of digits (36), we get a square (708516126756 = 841734²).

The spelling of 19681003521 in words is "nineteen billion, six hundred eighty-one million, three thousand, five hundred twenty-one".