20491890784704 has 1120 divisors, whose sum is σ = 68681845140480. Its totient is φ = 6010391642112.

The previous prime is 20491890784679. The next prime is 20491890784711. The reversal of 20491890784704 is 40748709819402.

20491890784704 is a `hidden beast` number, since 2 + 0 + 4 + 9 + 1 + 8 + 90 + 78 + 470 + 4 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 12366861444 + ... + 12366863100.

Almost surely, 2^{20491890784704} is an apocalyptic number.

20491890784704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20491890784704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34340922570240).

20491890784704 is an abundant number, since it is smaller than the sum of its proper divisors (48189954355776).

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

20491890784704 is a wasteful number, since it uses less digits than its factorization.

20491890784704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1879 (or 1860 counting only the distinct ones).

The product of its (nonzero) digits is 32514048, while the sum is 63.

The spelling of 20491890784704 in words is "twenty trillion, four hundred ninety-one billion, eight hundred ninety million, seven hundred eighty-four thousand, seven hundred four".