21299668 has 12 divisors (see below), whose sum is σ = 40141780. Its totient is φ = 9830592.

The previous prime is 21299647. The next prime is 21299669. The reversal of 21299668 is 86699212.

It can be written as a sum of positive squares in 2 ways, for example, as 14653584 + 6646084 = 3828^2 + 2578^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21299669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 204753 + ... + 204856.

Almost surely, 2^21299668 is an apocalyptic number.

It is an amenable number.

21299668 is a deficient number, since it is larger than the sum of its proper divisors (18842112).

21299668 is a wasteful number, since it uses less digits than its factorization.

21299668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409626 (or 409624 counting only the distinct ones).

The product of its digits is 93312, while the sum is 43.

The square root of 21299668 is about 4615.1563353802. The cubic root of 21299668 is about 277.1985439421.

The spelling of 21299668 in words is "twenty-one million, two hundred ninety-nine thousand, six hundred sixty-eight".