57221728 has 48 divisors (see below), whose sum is σ = 120022560. Its totient is φ = 26761216.

The previous prime is 57221719. The next prime is 57221729. The reversal of 57221728 is 82712275.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a junction number, because it is equal to n+sod(n) for n = 57221693 and 57221702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (57221729) 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, 159213 + ... + 159571.

It is an arithmetic number, because the mean of its divisors is an integer number (2500470).

Almost surely, 2^57221728 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 57221728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60011280).

57221728 is an abundant number, since it is smaller than the sum of its proper divisors (62800832).

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

57221728 is a wasteful number, since it uses less digits than its factorization.

57221728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 679 (or 671 counting only the distinct ones).

The product of its digits is 15680, while the sum is 34.

The square root of 57221728 is about 7564.5044781532. The cubic root of 57221728 is about 385.3484852807.

The spelling of 57221728 in words is "fifty-seven million, two hundred twenty-one thousand, seven hundred twenty-eight".