21297993 has 8 divisors (see below), whose sum is σ = 29892000. Its totient is φ = 13451328.

The previous prime is 21297979. The next prime is 21298001. The reversal of 21297993 is 39979212.

It is a happy number.

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

It is not a de Polignac number, because 21297993 - 2⁶ = 21297929 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21297953) 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, 186768 + ... + 186881.

It is an arithmetic number, because the mean of its divisors is an integer number (3736500).

Almost surely, 2^21297993 is an apocalyptic number.

It is an amenable number.

21297993 is a deficient number, since it is larger than the sum of its proper divisors (8594007).

21297993 is a wasteful number, since it uses less digits than its factorization.

21297993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373671.

The product of its digits is 61236, while the sum is 42.

The square root of 21297993 is about 4614.9748645036. The cubic root of 21297993 is about 277.1912774794.

The spelling of 21297993 in words is "twenty-one million, two hundred ninety-seven thousand, nine hundred ninety-three".