21313421 has 8 divisors (see below), whose sum is σ = 22509600. Its totient is φ = 20124720.

The previous prime is 21313379. The next prime is 21313429. The reversal of 21313421 is 12431312.

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 21313421 - 2¹⁴ = 21297037 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 21313421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21313429) 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, 4595 + ... + 7983.

It is an arithmetic number, because the mean of its divisors is an integer number (2813700).

Almost surely, 2^21313421 is an apocalyptic number.

It is an amenable number.

21313421 is a deficient number, since it is larger than the sum of its proper divisors (1196179).

21313421 is a wasteful number, since it uses less digits than its factorization.

21313421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3739.

The product of its digits is 144, while the sum is 17.

The square root of 21313421 is about 4616.6460769697. The cubic root of 21313421 is about 277.2581926237.

Adding to 21313421 its reverse (12431312), we get a palindrome (33744733).

The spelling of 21313421 in words is "twenty-one million, three hundred thirteen thousand, four hundred twenty-one".