19664048641 has 4 divisors (see below), whose sum is σ = 19672323652. Its totient is φ = 19655773632.

The previous prime is 19664048629. The next prime is 19664048653. The reversal of 19664048641 is 14684046691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 14684046691 = 35677 ⋅411583.

It is an interprime number because it is at equal distance from previous prime (19664048629) and next prime (19664048653).

It can be written as a sum of positive squares in 2 ways, for example, as 9740900416 + 9923148225 = 98696^2 + 99615^2 .

It is a cyclic number.

It is not a de Polignac number, because 19664048641 - 2¹⁵ = 19664015873 is a prime.

It is a super-2 number, since 2×19664048641² (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 (19664048441) 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, 4133940 + ... + 4138693.

It is an arithmetic number, because the mean of its divisors is an integer number (4918080913).

Almost surely, 2^19664048641 is an apocalyptic number.

It is an amenable number.

19664048641 is a deficient number, since it is larger than the sum of its proper divisors (8275011).

19664048641 is an equidigital number, since it uses as much as digits as its factorization.

19664048641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8275010.

The product of its (nonzero) digits is 995328, while the sum is 49.

The spelling of 19664048641 in words is "nineteen billion, six hundred sixty-four million, forty-eight thousand, six hundred forty-one".