51391304640 has 504 divisors, whose sum is σ = 202699821168. Its totient is φ = 11904122880.

The previous prime is 51391304603. The next prime is 51391304659. The reversal of 51391304640 is 4640319315.

51391304640 is a `hidden beast` number, since 5 + 1 + 3 + 9 + 1 + 3 + 0 + 4 + 640 = 666.

51391304640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 51391304595 and 51391304604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 8271135 + ... + 8277345.

Almost surely, 2^51391304640 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 51391304640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101349910584).

51391304640 is an abundant number, since it is smaller than the sum of its proper divisors (151308516528).

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

51391304640 is a wasteful number, since it uses less digits than its factorization.

51391304640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6277 (or 6251 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The spelling of 51391304640 in words is "fifty-one billion, three hundred ninety-one million, three hundred four thousand, six hundred forty".