30121728 has 144 divisors (see below), whose sum is σ = 98896896. Its totient is φ = 7925760.

The previous prime is 30121723. The next prime is 30121753. The reversal of 30121728 is 82712103.

It is a hoax number, since the sum of its digits (24) 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 (24).

It is a junction number, because it is equal to n+sod(n) for n = 30121698 and 30121707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30121723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69673 + ... + 70103.

It is an arithmetic number, because the mean of its divisors is an integer number (686784).

Almost surely, 2^30121728 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 30121728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49448448).

30121728 is an abundant number, since it is smaller than the sum of its proper divisors (68775168).

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

30121728 is a wasteful number, since it uses less digits than its factorization.

30121728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470 (or 456 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 30121728 is about 5488.3265208987. The cubic root of 30121728 is about 311.1429470067.

The spelling of 30121728 in words is "thirty million, one hundred twenty-one thousand, seven hundred twenty-eight".