51204240 has 180 divisors, whose sum is σ = 182409084. Its totient is φ = 12870144.

The previous prime is 51204229. The next prime is 51204247. The reversal of 51204240 is 4240215.

It can be written as a sum of positive squares in 2 ways, for example, as 37896336 + 13307904 = 6156^2 + 3648^2 .

It is a tau number, because it is divible by the number of its divisors (180).

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 (51204247) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 259822 + ... + 260018.

Almost surely, 2^51204240 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 51204240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91204542).

51204240 is an abundant number, since it is smaller than the sum of its proper divisors (131204844).

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

51204240 is a wasteful number, since it uses less digits than its factorization.

51204240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254 (or 226 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 51204240 is about 7155.7138008727. The cubic root of 51204240 is about 371.3373565814.

Adding to 51204240 its reverse (4240215), we get a palindrome (55444455).

The spelling of 51204240 in words is "fifty-one million, two hundred four thousand, two hundred forty".