51685728 has 48 divisors (see below), whose sum is σ = 137604096. Its totient is φ = 16983680.

The previous prime is 51685723. The next prime is 51685741. The reversal of 51685728 is 82758615.

It is a tau number, because it is divible by the number of its divisors (48).

It is a self number, because there is not a number n which added to its sum of digits gives 51685728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51685723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3025 + ... + 10607.

It is an arithmetic number, because the mean of its divisors is an integer number (2866752).

Almost surely, 2^51685728 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 51685728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68802048).

51685728 is an abundant number, since it is smaller than the sum of its proper divisors (85918368).

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

51685728 is a wasteful number, since it uses less digits than its factorization.

51685728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7667 (or 7659 counting only the distinct ones).

The product of its digits is 134400, while the sum is 42.

The square root of 51685728 is about 7189.2786842631. The cubic root of 51685728 is about 372.4976574481.

The spelling of 51685728 in words is "fifty-one million, six hundred eighty-five thousand, seven hundred twenty-eight".