20705336640 has 280 divisors, whose sum is σ = 77530817760. Its totient is φ = 5230697472.

The previous prime is 20705336629. The next prime is 20705336681. The reversal of 20705336640 is 4663350702.

20705336640 is a `hidden beast` number, since 2 + 0 + 7 + 0 + 5 + 3 + 3 + 6 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 20705336595 and 20705336604.

It is a congruent number.

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 39 ways as a sum of consecutive naturals, for example, 471459 + ... + 513501.

Almost surely, 2^20705336640 is an apocalyptic number.

20705336640 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 20705336640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38765408880).

20705336640 is an abundant number, since it is smaller than the sum of its proper divisors (56825481120).

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

20705336640 is a wasteful number, since it uses less digits than its factorization.

20705336640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42091 (or 42072 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 36.

The spelling of 20705336640 in words is "twenty billion, seven hundred five million, three hundred thirty-six thousand, six hundred forty".