51808688640 has 1120 divisors, whose sum is σ = 208671572736. Its totient is φ = 12262440960.

The previous prime is 51808688639. The next prime is 51808688641. The reversal of 51808688640 is 4688680815.

51808688640 is a `hidden beast` number, since 518 + 0 + 8 + 6 + 8 + 86 + 40 = 666.

It is an interprime number because it is at equal distance from previous prime (51808688639) and next prime (51808688641).

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

It is not an unprimeable number, because it can be changed into a prime (51808688641) by changing a digit.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 729699805 + ... + 729699875.

Almost surely, 2^51808688640 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 51808688640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104335786368).

51808688640 is an abundant number, since it is smaller than the sum of its proper divisors (156862884096).

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

51808688640 is an equidigital number, since it uses as much as digits as its factorization.

51808688640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152 (or 121 counting only the distinct ones).

The product of its (nonzero) digits is 2949120, while the sum is 54.

The spelling of 51808688640 in words is "fifty-one billion, eight hundred eight million, six hundred eighty-eight thousand, six hundred forty".