21667899 has 8 divisors (see below), whose sum is σ = 31516992. Its totient is φ = 13132040.

The previous prime is 21667879. The next prime is 21667913. The reversal of 21667899 is 99876612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21667899 - 2¹⁹ = 21143611 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21667859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 328269 + ... + 328334.

It is an arithmetic number, because the mean of its divisors is an integer number (3939624).

Almost surely, 2^21667899 is an apocalyptic number.

21667899 is a deficient number, since it is larger than the sum of its proper divisors (9849093).

21667899 is a wasteful number, since it uses less digits than its factorization.

21667899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656617.

The product of its digits is 326592, while the sum is 48.

The square root of 21667899 is about 4654.8790532086. The cubic root of 21667899 is about 278.7868388911.

The spelling of 21667899 in words is "twenty-one million, six hundred sixty-seven thousand, eight hundred ninety-nine".