51780820 has 96 divisors (see below), whose sum is σ = 139765248. Its totient is φ = 15662592.

The previous prime is 51780779. The next prime is 51780829. The reversal of 51780820 is 2808715.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51780829) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41242 + ... + 42478.

It is an arithmetic number, because the mean of its divisors is an integer number (1455888).

Almost surely, 2^51780820 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 51780820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (69882624).

51780820 is an abundant number, since it is smaller than the sum of its proper divisors (87984428).

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

51780820 is a wasteful number, since it uses less digits than its factorization.

51780820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1289 (or 1287 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 31.

The square root of 51780820 is about 7195.8891042039. The cubic root of 51780820 is about 372.7259593269.

The spelling of 51780820 in words is "fifty-one million, seven hundred eighty thousand, eight hundred twenty".