20664191818 has 8 divisors (see below), whose sum is σ = 30996963360. Its totient is φ = 10331870700.

The previous prime is 20664191789. The next prime is 20664191819. The reversal of 20664191818 is 81819146602.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (20664191819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47773 + ... + 208831.

It is an arithmetic number, because the mean of its divisors is an integer number (3874620420).

Almost surely, 2^20664191818 is an apocalyptic number.

20664191818 is a deficient number, since it is larger than the sum of its proper divisors (10332771542).

20664191818 is a wasteful number, since it uses less digits than its factorization.

20664191818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225212.

The product of its (nonzero) digits is 165888, while the sum is 46.

The spelling of 20664191818 in words is "twenty billion, six hundred sixty-four million, one hundred ninety-one thousand, eight hundred eighteen".