51421840 has 40 divisors (see below), whose sum is σ = 120673080. Its totient is φ = 20376576.

The previous prime is 51421817. The next prime is 51421861. The reversal of 51421840 is 4812415.

It can be written as a sum of positive squares in 4 ways, for example, as 19927296 + 31494544 = 4464^2 + 5612^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5772 + ... + 11668.

It is an arithmetic number, because the mean of its divisors is an integer number (3016827).

Almost surely, 2^51421840 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 51421840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60336540).

51421840 is an abundant number, since it is smaller than the sum of its proper divisors (69251240).

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

51421840 is a wasteful number, since it uses less digits than its factorization.

51421840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6019 (or 6013 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 25.

The square root of 51421840 is about 7170.9023142140. The cubic root of 51421840 is about 371.8626308999.

The spelling of 51421840 in words is "fifty-one million, four hundred twenty-one thousand, eight hundred forty".