21143686 has 4 divisors (see below), whose sum is σ = 31715532. Its totient is φ = 10571842.

The previous prime is 21143671. The next prime is 21143719. The reversal of 21143686 is 68634112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5285920 + ... + 5285923.

It is an arithmetic number, because the mean of its divisors is an integer number (7928883).

Almost surely, 2^21143686 is an apocalyptic number.

21143686 is a deficient number, since it is larger than the sum of its proper divisors (10571846).

21143686 is a wasteful number, since it uses less digits than its factorization.

21143686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10571845.

The product of its digits is 6912, while the sum is 31.

The square root of 21143686 is about 4598.2263972101. The cubic root of 21143686 is about 276.5202241081.

Adding to 21143686 its reverse (68634112), we get a palindrome (89777798).

The spelling of 21143686 in words is "twenty-one million, one hundred forty-three thousand, six hundred eighty-six".