215731728 has 160 divisors (see below), whose sum is σ = 649958400. Its totient is φ = 68428800.

The previous prime is 215731723. The next prime is 215731729. The reversal of 215731728 is 827137512.

215731728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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 = 215731692 and 215731701.

It is not an unprimeable number, because it can be changed into a prime (215731723) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1191798 + ... + 1191978.

It is an arithmetic number, because the mean of its divisors is an integer number (4062240).

Almost surely, 2^215731728 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 215731728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (324979200).

215731728 is an abundant number, since it is smaller than the sum of its proper divisors (434226672).

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

215731728 is a wasteful number, since it uses less digits than its factorization.

215731728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318 (or 306 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 215731728 is about 14687.8088222852. The cubic root of 215731728 is about 599.7514970914.

The spelling of 215731728 in words is "two hundred fifteen million, seven hundred thirty-one thousand, seven hundred twenty-eight".