19726648729 has 4 divisors (see below), whose sum is σ = 19727005284. Its totient is φ = 19726292176.

The previous prime is 19726648709. The next prime is 19726648741. The reversal of 19726648729 is 92784662791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 92784662791 = 159463 ⋅581857.

It can be written as a sum of positive squares in 2 ways, for example, as 12941337600 + 6785311129 = 113760^2 + 82373^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19726648729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19726648709) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75562 + ... + 212515.

It is an arithmetic number, because the mean of its divisors is an integer number (4931751321).

Almost surely, 2^19726648729 is an apocalyptic number.

It is an amenable number.

19726648729 is a deficient number, since it is larger than the sum of its proper divisors (356555).

19726648729 is an equidigital number, since it uses as much as digits as its factorization.

19726648729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356554.

The product of its digits is 18289152, while the sum is 61.

The spelling of 19726648729 in words is "nineteen billion, seven hundred twenty-six million, six hundred forty-eight thousand, seven hundred twenty-nine".