30991128 has 144 divisors (see below), whose sum is σ = 96423480. Its totient is φ = 8273664.

The previous prime is 30991127. The next prime is 30991139. The reversal of 30991128 is 82119903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30991123) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 424500 + ... + 424572.

Almost surely, 2^30991128 is an apocalyptic number.

30991128 is a gapful number since it is divisible by the number (38) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 30991128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48211740).

30991128 is an abundant number, since it is smaller than the sum of its proper divisors (65432352).

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

30991128 is a wasteful number, since it uses less digits than its factorization.

30991128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134 (or 104 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 30991128 is about 5566.9675766974. The cubic root of 30991128 is about 314.1080942839.

The spelling of 30991128 in words is "thirty million, nine hundred ninety-one thousand, one hundred twenty-eight".