20891966505488 has 40 divisors (see below), whose sum is σ = 43592561439168. Its totient is φ = 9642297923712.

The previous prime is 20891966505479. The next prime is 20891966505497. The reversal of 20891966505488 is 88450566919802.

It is an interprime number because it is at equal distance from previous prime (20891966505479) and next prime (20891966505497).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13424495 + ... + 14899697.

Almost surely, 2^{20891966505488} is an apocalyptic number.

It is an amenable number.

20891966505488 is an abundant number, since it is smaller than the sum of its proper divisors (22700594933680).

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

20891966505488 is a wasteful number, since it uses less digits than its factorization.

20891966505488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1543311 (or 1543305 counting only the distinct ones).

The product of its (nonzero) digits is 298598400, while the sum is 71.

The spelling of 20891966505488 in words is "twenty trillion, eight hundred ninety-one billion, nine hundred sixty-six million, five hundred five thousand, four hundred eighty-eight".