51855440 has 160 divisors (see below), whose sum is σ = 157489920. Its totient is φ = 15409152.

The previous prime is 51855439. The next prime is 51855443. The reversal of 51855440 is 4455815.

It is a junction number, because it is equal to n+sod(n) for n = 51855397 and 51855406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51855443) 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, 123551 + ... + 123969.

It is an arithmetic number, because the mean of its divisors is an integer number (984312).

Almost surely, 2^51855440 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 51855440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78744960).

51855440 is an abundant number, since it is smaller than the sum of its proper divisors (105634480).

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

51855440 is a wasteful number, since it uses less digits than its factorization.

51855440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469 (or 463 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 32.

The square root of 51855440 is about 7201.0721423966. The cubic root of 51855440 is about 372.9049153037.

The spelling of 51855440 in words is "fifty-one million, eight hundred fifty-five thousand, four hundred forty".