30721040 has 120 divisors (see below), whose sum is σ = 88166232. Its totient is φ = 9891840.

The previous prime is 30721027. The next prime is 30721073. The reversal of 30721040 is 4012703.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4177936 + 26543104 = 2044^2 + 5152^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66410 + ... + 66870.

Almost surely, 2^30721040 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 30721040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44083116).

30721040 is an abundant number, since it is smaller than the sum of its proper divisors (57445192).

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

30721040 is a wasteful number, since it uses less digits than its factorization.

30721040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505 (or 492 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 30721040 is about 5542.6564028451. The cubic root of 30721040 is about 313.1929455091.

Adding to 30721040 its reverse (4012703), we get a palindrome (34733743).

The spelling of 30721040 in words is "thirty million, seven hundred twenty-one thousand, forty".