51705987840 has 216 divisors, whose sum is σ = 192659223120. Its totient is φ = 12727590912.

The previous prime is 51705987833. The next prime is 51705987841. The reversal of 51705987840 is 4878950715.

51705987840 is a `hidden beast` number, since 5 + 1 + 7 + 0 + 598 + 7 + 8 + 40 = 666.

It is not an unprimeable number, because it can be changed into a prime (51705987841) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 22870 + ... + 322389.

Almost surely, 2^51705987840 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 51705987840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96329611560).

51705987840 is an abundant number, since it is smaller than the sum of its proper divisors (140953235280).

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

51705987840 is a wasteful number, since it uses less digits than its factorization.

51705987840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345299 (or 345282 counting only the distinct ones).

The product of its (nonzero) digits is 2822400, while the sum is 54.

The spelling of 51705987840 in words is "fifty-one billion, seven hundred five million, nine hundred eighty-seven thousand, eight hundred forty".