30721440 has 96 divisors (see below), whose sum is σ = 100154880. Its totient is φ = 7906304.

The previous prime is 30721429. The next prime is 30721447. The reversal of 30721440 is 4412703.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30721447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12817 + ... + 15023.

It is an arithmetic number, because the mean of its divisors is an integer number (1043280).

Almost surely, 2^30721440 is an apocalyptic number.

30721440 is a gapful number since it is divisible by the number (30) 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 30721440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50077440).

30721440 is an abundant number, since it is smaller than the sum of its proper divisors (69433440).

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

30721440 is a wasteful number, since it uses less digits than its factorization.

30721440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2254 (or 2246 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 30721440 is about 5542.6924865087. The cubic root of 30721440 is about 313.1943048016.

The spelling of 30721440 in words is "thirty million, seven hundred twenty-one thousand, four hundred forty".