20664191820 has 24 divisors (see below), whose sum is σ = 57859737264. Its totient is φ = 5510451136.

The previous prime is 20664191819. The next prime is 20664191837. The reversal of 20664191820 is 2819146602.

It is a zygodrome in base 11.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 172201539 + ... + 172201658.

It is an arithmetic number, because the mean of its divisors is an integer number (2410822386).

Almost surely, 2^20664191820 is an apocalyptic number.

20664191820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20664191820 is an abundant number, since it is smaller than the sum of its proper divisors (37195545444).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20664191820 is a wasteful number, since it uses less digits than its factorization.

20664191820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344403209 (or 344403207 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 39.

The spelling of 20664191820 in words is "twenty billion, six hundred sixty-four million, one hundred ninety-one thousand, eight hundred twenty".