19561936815 has 48 divisors (see below), whose sum is σ = 34844191200. Its totient is φ = 10145108736.

The previous prime is 19561936781. The next prime is 19561936841. The reversal of 19561936815 is 51863916591.

19561936815 is a `hidden beast` number, since 1 + 9 + 5 + 619 + 3 + 6 + 8 + 15 = 666.

It is not a de Polignac number, because 19561936815 - 2¹⁰ = 19561935791 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5174596 + ... + 5178374.

It is an arithmetic number, because the mean of its divisors is an integer number (725920650).

Almost surely, 2^19561936815 is an apocalyptic number.

19561936815 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

19561936815 is a deficient number, since it is larger than the sum of its proper divisors (15282254385).

19561936815 is a wasteful number, since it uses less digits than its factorization.

19561936815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6936 (or 6933 counting only the distinct ones).

The product of its digits is 1749600, while the sum is 54.

The spelling of 19561936815 in words is "nineteen billion, five hundred sixty-one million, nine hundred thirty-six thousand, eight hundred fifteen".