21143684 has 6 divisors (see below), whose sum is σ = 37001454. Its totient is φ = 10571840.

The previous prime is 21143671. The next prime is 21143719. The reversal of 21143684 is 48634112.

It can be written as a sum of positive squares in only one way, i.e., 19998784 + 1144900 = 4472^2 + 1070^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2642957 + ... + 2642964.

It is an arithmetic number, because the mean of its divisors is an integer number (6166909).

Almost surely, 2^21143684 is an apocalyptic number.

It is an amenable number.

21143684 is a deficient number, since it is larger than the sum of its proper divisors (15857770).

21143684 is a wasteful number, since it uses less digits than its factorization.

21143684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5285925 (or 5285923 counting only the distinct ones).

The product of its digits is 4608, while the sum is 29.

The square root of 21143684 is about 4598.2261797350. The cubic root of 21143684 is about 276.5202153894.

Adding to 21143684 its reverse (48634112), we get a palindrome (69777796).

The spelling of 21143684 in words is "twenty-one million, one hundred forty-three thousand, six hundred eighty-four".