21304040 has 16 divisors (see below), whose sum is σ = 47934180. Its totient is φ = 8521600.

The previous prime is 21304027. The next prime is 21304061. The reversal of 21304040 is 4040312.

It can be written as a sum of positive squares in 2 ways, for example, as 21215236 + 88804 = 4606^2 + 298^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 266261 + ... + 266340.

Almost surely, 2^21304040 is an apocalyptic number.

21304040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21304040 is an abundant number, since it is smaller than the sum of its proper divisors (26630140).

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

21304040 is a wasteful number, since it uses less digits than its factorization.

21304040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 532612 (or 532608 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21304040 is about 4615.6299678375. The cubic root of 21304040 is about 277.2175086998.

Adding to 21304040 its reverse (4040312), we get a palindrome (25344352).

The spelling of 21304040 in words is "twenty-one million, three hundred four thousand, forty".