20815648881889 has 9 divisors (see below), whose sum is σ = 20926077970161. Its totient is φ = 20705799567780.

The previous prime is 20815648881871. The next prime is 20815648881913. The reversal of 20815648881889 is 98818884651802.

The square root of 20815648881889 is 4562417.

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

It is not a de Polignac number, because 20815648881889 - 2¹⁹ = 20815648357601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20815648881869) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 871409704 + ... + 871433590.

Almost surely, 2^{20815648881889} is an apocalyptic number.

20815648881889 is the 4562417-th square number.

20815648881889 is the 2281209-th centered octagonal number.

It is an amenable number.

20815648881889 is a deficient number, since it is larger than the sum of its proper divisors (110429088272).

20815648881889 is an frugal number, since it uses more digits than its factorization.

20815648881889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48156 (or 24078 counting only the distinct ones).

The product of its (nonzero) digits is 566231040, while the sum is 76.

The spelling of 20815648881889 in words is "twenty trillion, eight hundred fifteen billion, six hundred forty-eight million, eight hundred eighty-one thousand, eight hundred eighty-nine".