51009840 has 240 divisors, whose sum is σ = 203112000. Its totient is φ = 11225088.

The previous prime is 51009817. The next prime is 51009853. The reversal of 51009840 is 4890015.

It is a tau number, because it is divible by the number of its divisors (240).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 145986 + ... + 146334.

It is an arithmetic number, because the mean of its divisors is an integer number (846300).

Almost surely, 2^51009840 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 51009840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101556000).

51009840 is an abundant number, since it is smaller than the sum of its proper divisors (152102160).

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

51009840 is a wasteful number, since it uses less digits than its factorization.

51009840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404 (or 395 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 51009840 is about 7142.1173331163. The cubic root of 51009840 is about 370.8668256863.

Adding to 51009840 its reverse (4890015), we get a palindrome (55899855).

The spelling of 51009840 in words is "fifty-one million, nine thousand, eight hundred forty".