21917198 has 8 divisors (see below), whose sum is σ = 32926392. Its totient is φ = 10941736.

The previous prime is 21917177. The next prime is 21917201. The reversal of 21917198 is 89171912.

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

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 6740 + ... + 9447.

It is an arithmetic number, because the mean of its divisors is an integer number (4115799).

Almost surely, 2^21917198 is an apocalyptic number.

21917198 is a deficient number, since it is larger than the sum of its proper divisors (11009194).

21917198 is a wasteful number, since it uses less digits than its factorization.

21917198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16866.

The product of its digits is 9072, while the sum is 38.

The square root of 21917198 is about 4681.5807159548. The cubic root of 21917198 is about 279.8519540496.

The spelling of 21917198 in words is "twenty-one million, nine hundred seventeen thousand, one hundred ninety-eight".