21304340 has 12 divisors (see below), whose sum is σ = 44739156. Its totient is φ = 8521728.

The previous prime is 21304333. The next prime is 21304351. The reversal of 21304340 is 4340312.

It can be written as a sum of positive squares in 2 ways, for example, as 14730244 + 6574096 = 3838^2 + 2564^2 .

It is a congruent number.

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, 532589 + ... + 532628.

It is an arithmetic number, because the mean of its divisors is an integer number (3728263).

Almost surely, 2^21304340 is an apocalyptic number.

21304340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21304340 is an abundant number, since it is smaller than the sum of its proper divisors (23434816).

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

21304340 is a wasteful number, since it uses less digits than its factorization.

21304340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1065226 (or 1065224 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21304340 is about 4615.6624659955. The cubic root of 21304340 is about 277.2188099375.

Adding to 21304340 its reverse (4340312), we get a palindrome (25644652).

The spelling of 21304340 in words is "twenty-one million, three hundred four thousand, three hundred forty".