21198999 has 8 divisors (see below), whose sum is σ = 28583280. Its totient is φ = 13973696.

The previous prime is 21198997. The next prime is 21199019. The reversal of 21198999 is 99989112.

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 21198999 - 2¹ = 21198997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21198997) 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 in 7 ways as a sum of consecutive naturals, for example, 39432 + ... + 39965.

It is an arithmetic number, because the mean of its divisors is an integer number (3572910).

Almost surely, 2^21198999 is an apocalyptic number.

21198999 is a deficient number, since it is larger than the sum of its proper divisors (7384281).

21198999 is an equidigital number, since it uses as much as digits as its factorization.

21198999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79489.

The product of its digits is 104976, while the sum is 48.

The square root of 21198999 is about 4604.2370703516. The cubic root of 21198999 is about 276.7611446499.

The spelling of 21198999 in words is "twenty-one million, one hundred ninety-eight thousand, nine hundred ninety-nine".