51000840 has 256 divisors, whose sum is σ = 191289600. Its totient is φ = 12130560.

The previous prime is 51000751. The next prime is 51000841. The reversal of 51000840 is 4800015.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51000841) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 962254 + ... + 962306.

It is an arithmetic number, because the mean of its divisors is an integer number (747225).

Almost surely, 2^51000840 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 51000840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95644800).

51000840 is an abundant number, since it is smaller than the sum of its proper divisors (140288760).

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

51000840 is a wasteful number, since it uses less digits than its factorization.

51000840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96 (or 74 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 51000840 is about 7141.4872400642. The cubic root of 51000840 is about 370.8450129161.

Adding to 51000840 its reverse (4800015), we get a palindrome (55800855).

The spelling of 51000840 in words is "fifty-one million, eight hundred forty", and thus it is an aban number.