51986694816 has 144 divisors (see below), whose sum is σ = 169715879424. Its totient is φ = 14786606592.

The previous prime is 51986694811. The next prime is 51986694853. The reversal of 51986694816 is 61849668915.

51986694816 is a `hidden beast` number, since 5 + 1 + 98 + 6 + 69 + 481 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (51986694811) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 391750 + ... + 507386.

It is an arithmetic number, because the mean of its divisors is an integer number (1178582496).

Almost surely, 2^51986694816 is an apocalyptic number.

51986694816 is a gapful number since it is divisible by the number (56) 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 51986694816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84857939712).

51986694816 is an abundant number, since it is smaller than the sum of its proper divisors (117729184608).

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

51986694816 is a wasteful number, since it uses less digits than its factorization.

51986694816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115883 (or 115872 counting only the distinct ones).

The product of its digits is 22394880, while the sum is 63.

The spelling of 51986694816 in words is "fifty-one billion, nine hundred eighty-six million, six hundred ninety-four thousand, eight hundred sixteen".