21211868 has 6 divisors (see below), whose sum is σ = 37120776. Its totient is φ = 10605932.

The previous prime is 21211867. The next prime is 21211873. The reversal of 21211868 is 86811212.

It is a self number, because there is not a number n which added to its sum of digits gives 21211868.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2651480 + ... + 2651487.

It is an arithmetic number, because the mean of its divisors is an integer number (6186796).

Almost surely, 2^21211868 is an apocalyptic number.

It is an amenable number.

21211868 is a deficient number, since it is larger than the sum of its proper divisors (15908908).

21211868 is a wasteful number, since it uses less digits than its factorization.

21211868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5302971 (or 5302969 counting only the distinct ones).

The product of its digits is 1536, while the sum is 29.

The square root of 21211868 is about 4605.6343754145. The cubic root of 21211868 is about 276.8171365815.

The spelling of 21211868 in words is "twenty-one million, two hundred eleven thousand, eight hundred sixty-eight".