51781403520 has 512 divisors, whose sum is σ = 228651033600. Its totient is φ = 10759495680.

The previous prime is 51781403503. The next prime is 51781403561. The reversal of 51781403520 is 2530418715.

51781403520 is a `hidden beast` number, since 5 + 17 + 81 + 40 + 3 + 520 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1311102 + ... + 1350018.

It is an arithmetic number, because the mean of its divisors is an integer number (446584050).

Almost surely, 2^51781403520 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 51781403520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114325516800).

51781403520 is an abundant number, since it is smaller than the sum of its proper divisors (176869630080).

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

51781403520 is a wasteful number, since it uses less digits than its factorization.

51781403520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38963 (or 38945 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The spelling of 51781403520 in words is "fifty-one billion, seven hundred eighty-one million, four hundred three thousand, five hundred twenty".