30721236 has 72 divisors (see below), whose sum is σ = 89822880. Its totient is φ = 8100288.

The previous prime is 30721231. The next prime is 30721253. The reversal of 30721236 is 63212703.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (30721231) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5635 + ... + 9653.

It is an arithmetic number, because the mean of its divisors is an integer number (1247540).

Almost surely, 2^30721236 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 30721236, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44911440).

30721236 is an abundant number, since it is smaller than the sum of its proper divisors (59101644).

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

30721236 is a wasteful number, since it uses less digits than its factorization.

30721236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4053 (or 4044 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 24.

The square root of 30721236 is about 5542.6740838696. The cubic root of 30721236 is about 313.1936115639.

Adding to 30721236 its reverse (63212703), we get a palindrome (93933939).

The spelling of 30721236 in words is "thirty million, seven hundred twenty-one thousand, two hundred thirty-six".