21011304 has 48 divisors (see below), whose sum is σ = 54336960. Its totient is φ = 6770400.

The previous prime is 21011299. The next prime is 21011317. The reversal of 21011304 is 40311012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21011304.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22609 + ... + 23519.

It is an arithmetic number, because the mean of its divisors is an integer number (1132020).

Almost surely, 2^21011304 is an apocalyptic number.

21011304 is a gapful number since it is divisible by the number (24) 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 21011304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27168480).

21011304 is an abundant number, since it is smaller than the sum of its proper divisors (33325656).

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

21011304 is a wasteful number, since it uses less digits than its factorization.

21011304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 982 (or 947 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21011304 is about 4583.8088965401. The cubic root of 21011304 is about 275.9419117409.

Adding to 21011304 its reverse (40311012), we get a palindrome (61322316).

The spelling of 21011304 in words is "twenty-one million, eleven thousand, three hundred four".