20991395034560 has 28 divisors (see below), whose sum is σ = 49985759426808. Its totient is φ = 8396558013696.

The previous prime is 20991395034541. The next prime is 20991395034593. The reversal of 20991395034560 is 6543059319902.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 20991395034496 and 20991395034505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32799054422 + ... + 32799055061.

Almost surely, 2^{20991395034560} is an apocalyptic number.

20991395034560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20991395034560 is an abundant number, since it is smaller than the sum of its proper divisors (28994364392248).

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

20991395034560 is an equidigital number, since it uses as much as digits as its factorization.

20991395034560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65598109500 (or 65598109490 counting only the distinct ones).

The product of its (nonzero) digits is 7873200, while the sum is 56.

The spelling of 20991395034560 in words is "twenty trillion, nine hundred ninety-one billion, three hundred ninety-five million, thirty-four thousand, five hundred sixty".