6781521920 has 104 divisors (see below), whose sum is σ = 16399233864. Its totient is φ = 2691694592.

The previous prime is 6781521919. The next prime is 6781521931. The reversal of 6781521920 is 291251876.

It can be written as a sum of positive squares in 4 ways, for example, as 2660909056 + 4120612864 = 51584^2 + 64192^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2804552 + ... + 2806968.

It is an arithmetic number, because the mean of its divisors is an integer number (157684941).

Almost surely, 2^6781521920 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6781521920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8199616932).

6781521920 is an abundant number, since it is smaller than the sum of its proper divisors (9617711944).

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

6781521920 is a wasteful number, since it uses less digits than its factorization.

6781521920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2583 (or 2561 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 6781521920 is about 82349.9964784456. The cubic root of 6781521920 is about 1892.8188687943.

The spelling of 6781521920 in words is "six billion, seven hundred eighty-one million, five hundred twenty-one thousand, nine hundred twenty".