21717998 has 8 divisors (see below), whose sum is σ = 32721192. Its totient is φ = 10810936.

The previous prime is 21717989. The next prime is 21718033. The reversal of 21717998 is 89971712.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23465 + ... + 24372.

It is an arithmetic number, because the mean of its divisors is an integer number (4090149).

Almost surely, 2^21717998 is an apocalyptic number.

21717998 is a deficient number, since it is larger than the sum of its proper divisors (11003194).

21717998 is a wasteful number, since it uses less digits than its factorization.

21717998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48066.

The product of its digits is 63504, while the sum is 44.

The square root of 21717998 is about 4660.2572890346. The cubic root of 21717998 is about 279.0015373133.

The spelling of 21717998 in words is "twenty-one million, seven hundred seventeen thousand, nine hundred ninety-eight".