51805440 has 144 divisors (see below), whose sum is σ = 183960000. Its totient is φ = 13805568.

The previous prime is 51805423. The next prime is 51805463. The reversal of 51805440 is 4450815.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×51805440² = 5367607227187200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33811 + ... + 35309.

It is an arithmetic number, because the mean of its divisors is an integer number (1277500).

Almost surely, 2^51805440 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 51805440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91980000).

51805440 is an abundant number, since it is smaller than the sum of its proper divisors (132154560).

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

51805440 is a wasteful number, since it uses less digits than its factorization.

51805440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1529 (or 1509 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 51805440 is about 7197.5995998666. The cubic root of 51805440 is about 372.7850227609.

The spelling of 51805440 in words is "fifty-one million, eight hundred five thousand, four hundred forty".