19665520918 has 4 divisors (see below), whose sum is σ = 29498281380. Its totient is φ = 9832760458.

The previous prime is 19665520883. The next prime is 19665520951. The reversal of 19665520918 is 81902556691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81902556691 = 9967 ⋅8217373.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4916380228 + ... + 4916380231.

It is an arithmetic number, because the mean of its divisors is an integer number (7374570345).

Almost surely, 2^19665520918 is an apocalyptic number.

19665520918 is a deficient number, since it is larger than the sum of its proper divisors (9832760462).

19665520918 is an equidigital number, since it uses as much as digits as its factorization.

19665520918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9832760461.

The product of its (nonzero) digits is 1166400, while the sum is 52.

The spelling of 19665520918 in words is "nineteen billion, six hundred sixty-five million, five hundred twenty thousand, nine hundred eighteen".