21642286 has 4 divisors (see below), whose sum is σ = 32463432. Its totient is φ = 10821142.

The previous prime is 21642281. The next prime is 21642289. The reversal of 21642286 is 68224612.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5410570 + ... + 5410573.

It is an arithmetic number, because the mean of its divisors is an integer number (8115858).

Almost surely, 2^21642286 is an apocalyptic number.

21642286 is a deficient number, since it is larger than the sum of its proper divisors (10821146).

21642286 is a wasteful number, since it uses less digits than its factorization.

21642286 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10821145.

The product of its digits is 9216, while the sum is 31.

The square root of 21642286 is about 4652.1270403978. The cubic root of 21642286 is about 278.6769469459.

Adding to 21642286 its reverse (68224612), we get a palindrome (89866898).

The spelling of 21642286 in words is "twenty-one million, six hundred forty-two thousand, two hundred eighty-six".