20856605552640 has 1456 divisors, whose sum is σ = 88168242466080. Its totient is φ = 4666734673920.

The previous prime is 20856605552581. The next prime is 20856605552659. The reversal of 20856605552640 is 4625550665802.

20856605552640 is a `hidden beast` number, since 2 + 0 + 8 + 5 + 6 + 60 + 55 + 526 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 2134973676 + ... + 2134983444.

Almost surely, 2^{20856605552640} is an apocalyptic number.

20856605552640 is a gapful number since it is divisible by the number (20) 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 20856605552640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44084121233040).

20856605552640 is an abundant number, since it is smaller than the sum of its proper divisors (67311636913440).

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

20856605552640 is an equidigital number, since it uses as much as digits as its factorization.

20856605552640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9840 (or 9803 counting only the distinct ones).

The product of its (nonzero) digits is 17280000, while the sum is 54.

The spelling of 20856605552640 in words is "twenty trillion, eight hundred fifty-six billion, six hundred five million, five hundred fifty-two thousand, six hundred forty".