21398493 has 8 divisors (see below), whose sum is σ = 28892800. Its totient is φ = 14084928.

The previous prime is 21398467. The next prime is 21398497. The reversal of 21398493 is 39489312.

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

It is not a de Polignac number, because 21398493 - 2²² = 17204189 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 (21398497) 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, 44908 + ... + 45381.

It is an arithmetic number, because the mean of its divisors is an integer number (3611600).

Almost surely, 2^21398493 is an apocalyptic number.

It is an amenable number.

21398493 is a deficient number, since it is larger than the sum of its proper divisors (7494307).

21398493 is an equidigital number, since it uses as much as digits as its factorization.

21398493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90371.

The product of its digits is 46656, while the sum is 39.

The square root of 21398493 is about 4625.8505163916. The cubic root of 21398493 is about 277.6265926751.

The spelling of 21398493 in words is "twenty-one million, three hundred ninety-eight thousand, four hundred ninety-three".