30728321 has 8 divisors (see below), whose sum is σ = 33653760. Its totient is φ = 27883152.

The previous prime is 30728293. The next prime is 30728381. The reversal of 30728321 is 12382703.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 30728321 - 2¹⁴ = 30711937 is a prime.

It is a super-2 number, since 2×30728321² = 1888459422958082, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (30728381) 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, 19265 + ... + 20798.

It is an arithmetic number, because the mean of its divisors is an integer number (4206720).

Almost surely, 2^30728321 is an apocalyptic number.

It is an amenable number.

30728321 is a deficient number, since it is larger than the sum of its proper divisors (2925439).

30728321 is a wasteful number, since it uses less digits than its factorization.

30728321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40135.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 30728321 is about 5543.3131789571. The cubic root of 30728321 is about 313.2176861832.

The spelling of 30728321 in words is "thirty million, seven hundred twenty-eight thousand, three hundred twenty-one".