51861680640 has 1920 divisors, whose sum is σ = 247088185344. Its totient is φ = 9732096000.

The previous prime is 51861680593. The next prime is 51861680659. The reversal of 51861680640 is 4608616815.

51861680640 is a `hidden beast` number, since 518 + 6 + 16 + 80 + 6 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (1920).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1264919020 + ... + 1264919060.

Almost surely, 2^51861680640 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 51861680640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123544092672).

51861680640 is an abundant number, since it is smaller than the sum of its proper divisors (195226504704).

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

51861680640 is a wasteful number, since it uses less digits than its factorization.

51861680640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 51861680640 in words is "fifty-one billion, eight hundred sixty-one million, six hundred eighty thousand, six hundred forty".