51306240 has 144 divisors (see below), whose sum is σ = 169537536. Its totient is φ = 13209600.

The previous prime is 51306239. The next prime is 51306247. The reversal of 51306240 is 4260315.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51306247) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 118825 + ... + 119255.

It is an arithmetic number, because the mean of its divisors is an integer number (1177344).

Almost surely, 2^51306240 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 51306240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (84768768).

51306240 is an abundant number, since it is smaller than the sum of its proper divisors (118231296).

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

51306240 is a wasteful number, since it uses less digits than its factorization.

51306240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486 (or 472 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 51306240 is about 7162.8374266069. The cubic root of 51306240 is about 371.5837638317.

Adding to 51306240 its reverse (4260315), we get a palindrome (55566555).

The spelling of 51306240 in words is "fifty-one million, three hundred six thousand, two hundred forty".