21568340 has 12 divisors (see below), whose sum is σ = 45293556. Its totient is φ = 8627328.

The previous prime is 21568333. The next prime is 21568357. The reversal of 21568340 is 4386512.

It can be written as a sum of positive squares in 2 ways, for example, as 3147076 + 18421264 = 1774^2 + 4292^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 539189 + ... + 539228.

It is an arithmetic number, because the mean of its divisors is an integer number (3774463).

Almost surely, 2^21568340 is an apocalyptic number.

21568340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21568340 is an abundant number, since it is smaller than the sum of its proper divisors (23725216).

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

21568340 is a wasteful number, since it uses less digits than its factorization.

21568340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1078426 (or 1078424 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 21568340 is about 4644.1726927409. The cubic root of 21568340 is about 278.3591961657.

The spelling of 21568340 in words is "twenty-one million, five hundred sixty-eight thousand, three hundred forty".