51643728 has 30 divisors (see below), whose sum is σ = 144531114. Its totient is φ = 17214528.

The previous prime is 51643721. The next prime is 51643769. The reversal of 51643728 is 82734615.

51643728 is a `hidden beast` number, since 5 + 1 + 643 + 7 + 2 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 29289744 + 22353984 = 5412^2 + 4728^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 51643692 and 51643701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51643721) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 179175 + ... + 179462.

Almost surely, 2^51643728 is an apocalyptic number.

It is an amenable number.

51643728 is an abundant number, since it is smaller than the sum of its proper divisors (92887386).

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

51643728 is a wasteful number, since it uses less digits than its factorization.

51643728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358651 (or 358642 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 51643728 is about 7186.3570743458. The cubic root of 51643728 is about 372.3967324808.

It can be divided in two parts, 516 and 43728, that added together give a palindrome (44244).

The spelling of 51643728 in words is "fifty-one million, six hundred forty-three thousand, seven hundred twenty-eight".