21393493 has 8 divisors (see below), whose sum is σ = 23721696. Its totient is φ = 19129200.

The previous prime is 21393481. The next prime is 21393521. The reversal of 21393493 is 39439312.

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 21393493 - 2⁵ = 21393461 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 (21393433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15271 + ... + 16612.

It is an arithmetic number, because the mean of its divisors is an integer number (2965212).

Almost surely, 2^21393493 is an apocalyptic number.

It is an amenable number.

21393493 is a deficient number, since it is larger than the sum of its proper divisors (2328203).

21393493 is a wasteful number, since it uses less digits than its factorization.

21393493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31955.

The product of its digits is 17496, while the sum is 34.

The square root of 21393493 is about 4625.3100436619. The cubic root of 21393493 is about 277.6049674592.

The spelling of 21393493 in words is "twenty-one million, three hundred ninety-three thousand, four hundred ninety-three".