19917959161 has 3 divisors (see below), whose sum is σ = 19918100293. Its totient is φ = 19917818030.

The previous prime is 19917959147. The next prime is 19917959197. The reversal of 19917959161 is 16195971991.

The square root of 19917959161 is 141131.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 19917959161 - 2⁹ = 19917958649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19917959096 and 19917959105.

It is not an unprimeable number, because it can be changed into a prime (19917959111) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 70566 + ... + 211696.

Almost surely, 2^19917959161 is an apocalyptic number.

19917959161 is the 141131-st square number.

19917959161 is the 70566-th centered octagonal number.

It is an amenable number.

19917959161 is a deficient number, since it is larger than the sum of its proper divisors (141132).

19917959161 is an frugal number, since it uses more digits than its factorization.

19917959161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282262 (or 141131 counting only the distinct ones).

The product of its digits is 1377810, while the sum is 58.

The spelling of 19917959161 in words is "nineteen billion, nine hundred seventeen million, nine hundred fifty-nine thousand, one hundred sixty-one".