21173998 has 8 divisors (see below), whose sum is σ = 31921200. Its totient is φ = 10533600.

The previous prime is 21173987. The next prime is 21174001. The reversal of 21173998 is 89937112.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21173998.

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 an upside-down number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26203 + ... + 26998.

It is an arithmetic number, because the mean of its divisors is an integer number (3990150).

Almost surely, 2^21173998 is an apocalyptic number.

21173998 is a deficient number, since it is larger than the sum of its proper divisors (10747202).

21173998 is a wasteful number, since it uses less digits than its factorization.

21173998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53402.

The product of its digits is 27216, while the sum is 40.

The square root of 21173998 is about 4601.5212701888. The cubic root of 21173998 is about 276.6523026042.

The spelling of 21173998 in words is "twenty-one million, one hundred seventy-three thousand, nine hundred ninety-eight".