51721564608 has 224 divisors, whose sum is σ = 179380408320. Its totient is φ = 14300789760.

The previous prime is 51721564567. The next prime is 51721564613. The reversal of 51721564608 is 80646512715.

51721564608 is a `hidden beast` number, since 5 + 1 + 7 + 21 + 564 + 60 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 306010 + ... + 443942.

Almost surely, 2^51721564608 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 51721564608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89690204160).

51721564608 is an abundant number, since it is smaller than the sum of its proper divisors (127658843712).

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

51721564608 is a wasteful number, since it uses less digits than its factorization.

51721564608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137992 (or 137976 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 51721564608 in words is "fifty-one billion, seven hundred twenty-one million, five hundred sixty-four thousand, six hundred eight".