51991797312 has 672 divisors, whose sum is σ = 193491916800. Its totient is φ = 13249474560.

The previous prime is 51991797301. The next prime is 51991797317. The reversal of 51991797312 is 21379719915.

51991797312 is a `hidden beast` number, since 519 + 9 + 1 + 7 + 97 + 31 + 2 = 666.

51991797312 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (672).

It is not an unprimeable number, because it can be changed into a prime (51991797317) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 79619578 + ... + 79620230.

It is an arithmetic number, because the mean of its divisors is an integer number (287934400).

Almost surely, 2^51991797312 is an apocalyptic number.

51991797312 is a gapful number since it is divisible by the number (52) 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 51991797312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96745958400).

51991797312 is an abundant number, since it is smaller than the sum of its proper divisors (141500119488).

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

51991797312 is a wasteful number, since it uses less digits than its factorization.

51991797312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 736 (or 709 counting only the distinct ones).

The product of its digits is 1071630, while the sum is 54.

The spelling of 51991797312 in words is "fifty-one billion, nine hundred ninety-one million, seven hundred ninety-seven thousand, three hundred twelve".