51440987520 has 640 divisors, whose sum is σ = 203281626240. Its totient is φ = 12314198016.

The previous prime is 51440987519. The next prime is 51440987527. The reversal of 51440987520 is 2578904415.

51440987520 is a `hidden beast` number, since 5 + 1 + 4 + 40 + 9 + 87 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51440987527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 24934009 + ... + 24936071.

It is an arithmetic number, because the mean of its divisors is an integer number (317627541).

Almost surely, 2^51440987520 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 51440987520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101640813120).

51440987520 is an abundant number, since it is smaller than the sum of its proper divisors (151840638720).

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

51440987520 is a wasteful number, since it uses less digits than its factorization.

51440987520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2144 (or 2123 counting only the distinct ones).

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

The spelling of 51440987520 in words is "fifty-one billion, four hundred forty million, nine hundred eighty-seven thousand, five hundred twenty".