51405240 has 64 divisors (see below), whose sum is σ = 155750400. Its totient is φ = 13571712.

The previous prime is 51405239. The next prime is 51405259. The reversal of 51405240 is 4250415.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10281 + ... + 14439.

It is an arithmetic number, because the mean of its divisors is an integer number (2433600).

Almost surely, 2^51405240 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 51405240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77875200).

51405240 is an abundant number, since it is smaller than the sum of its proper divisors (104345160).

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

51405240 is a wasteful number, since it uses less digits than its factorization.

51405240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4276 (or 4272 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 51405240 is about 7169.7447653316. The cubic root of 51405240 is about 371.8226116912.

Adding to 51405240 its reverse (4250415), we get a palindrome (55655655).

The spelling of 51405240 in words is "fifty-one million, four hundred five thousand, two hundred forty".