20813097921 has 16 divisors (see below), whose sum is σ = 34598396928. Its totient is φ = 10811998800.

The previous prime is 20813097911. The next prime is 20813097941. The reversal of 20813097921 is 12979031802.

It is not a de Polignac number, because 20813097921 - 2¹⁰ = 20813096897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20813097901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45049765 + ... + 45050226.

It is an arithmetic number, because the mean of its divisors is an integer number (2162399808).

Almost surely, 2^20813097921 is an apocalyptic number.

20813097921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20813097921 is a deficient number, since it is larger than the sum of its proper divisors (13785299007).

20813097921 is a wasteful number, since it uses less digits than its factorization.

20813097921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90100012.

The product of its (nonzero) digits is 54432, while the sum is 42.

The spelling of 20813097921 in words is "twenty billion, eight hundred thirteen million, ninety-seven thousand, nine hundred twenty-one".