51493840 has 40 divisors (see below), whose sum is σ = 120927528. Its totient is φ = 20390400.

The previous prime is 51493823. The next prime is 51493847. The reversal of 51493840 is 4839415.

51493840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 26132544 + 25361296 = 5112^2 + 5036^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 51493796 and 51493805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51493847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4894 + ... + 11266.

Almost surely, 2^51493840 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 51493840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60463764).

51493840 is an abundant number, since it is smaller than the sum of its proper divisors (69433688).

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

51493840 is a wasteful number, since it uses less digits than its factorization.

51493840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6487 (or 6481 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 51493840 is about 7175.9208468321. The cubic root of 51493840 is about 372.0361085696.

The spelling of 51493840 in words is "fifty-one million, four hundred ninety-three thousand, eight hundred forty".