21297493 has 8 divisors (see below), whose sum is σ = 24502400. Its totient is φ = 18133200.

The previous prime is 21297487. The next prime is 21297509. The reversal of 21297493 is 39479212.

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 21297493 - 2⁹ = 21296981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21297193) 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, 9018 + ... + 11131.

It is an arithmetic number, because the mean of its divisors is an integer number (3062800).

Almost surely, 2^21297493 is an apocalyptic number.

It is an amenable number.

21297493 is a deficient number, since it is larger than the sum of its proper divisors (3204907).

21297493 is a wasteful number, since it uses less digits than its factorization.

21297493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20307.

The product of its digits is 27216, while the sum is 37.

The square root of 21297493 is about 4614.9206927097. The cubic root of 21297493 is about 277.1891083122.

The spelling of 21297493 in words is "twenty-one million, two hundred ninety-seven thousand, four hundred ninety-three".