21643282 has 4 divisors (see below), whose sum is σ = 32464926. Its totient is φ = 10821640.

The previous prime is 21643267. The next prime is 21643289. The reversal of 21643282 is 28234612.

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

It can be written as a sum of positive squares in only one way, i.e., 20985561 + 657721 = 4581^2 + 811^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21643282.

It is not an unprimeable number, because it can be changed into a prime (21643289) by changing a digit.

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, 5410819 + ... + 5410822.

Almost surely, 2^21643282 is an apocalyptic number.

21643282 is a deficient number, since it is larger than the sum of its proper divisors (10821644).

21643282 is a wasteful number, since it uses less digits than its factorization.

21643282 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10821643.

The product of its digits is 4608, while the sum is 28.

The square root of 21643282 is about 4652.2340869737. The cubic root of 21643282 is about 278.6812218791.

Adding to 21643282 its reverse (28234612), we get a palindrome (49877894).

The spelling of 21643282 in words is "twenty-one million, six hundred forty-three thousand, two hundred eighty-two".