19717815947 has 4 divisors (see below), whose sum is σ = 19718388816. Its totient is φ = 19717243080.

The previous prime is 19717815893. The next prime is 19717815961. The reversal of 19717815947 is 74951871791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74951871791 = 7603 ⋅9858197.

It is a cyclic number.

It is not a de Polignac number, because 19717815947 - 2¹⁸ = 19717553803 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19717815977) 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, 231263 + ... + 304824.

It is an arithmetic number, because the mean of its divisors is an integer number (4929597204).

Almost surely, 2^19717815947 is an apocalyptic number.

19717815947 is a deficient number, since it is larger than the sum of its proper divisors (572869).

19717815947 is an equidigital number, since it uses as much as digits as its factorization.

19717815947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 572868.

The product of its digits is 4445280, while the sum is 59.

The spelling of 19717815947 in words is "nineteen billion, seven hundred seventeen million, eight hundred fifteen thousand, nine hundred forty-seven".