51685440 has 112 divisors (see below), whose sum is σ = 173809152. Its totient is φ = 12967936.

The previous prime is 51685397. The next prime is 51685451. The reversal of 51685440 is 4458615.

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, 14737 + ... + 17903.

Almost surely, 2^51685440 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 51685440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86904576).

51685440 is an abundant number, since it is smaller than the sum of its proper divisors (122123712).

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

51685440 is a wasteful number, since it uses less digits than its factorization.

51685440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3204 (or 3194 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 33.

The square root of 51685440 is about 7189.2586544094. The cubic root of 51685440 is about 372.4969655774.

It can be divided in two parts, 51685 and 440, that added together give a palindrome (52125).

The spelling of 51685440 in words is "fifty-one million, six hundred eighty-five thousand, four hundred forty".