21421313 has 4 divisors (see below), whose sum is σ = 21563328. Its totient is φ = 21279300.

The previous prime is 21421273. The next prime is 21421319. The reversal of 21421313 is 31312412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21421313 - 2⁶ = 21421249 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21421291 and 21421300.

It is not an unprimeable number, because it can be changed into a prime (21421319) 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 3 ways as a sum of consecutive naturals, for example, 70781 + ... + 71082.

It is an arithmetic number, because the mean of its divisors is an integer number (5390832).

Almost surely, 2^21421313 is an apocalyptic number.

It is an amenable number.

21421313 is a deficient number, since it is larger than the sum of its proper divisors (142015).

21421313 is a wasteful number, since it uses less digits than its factorization.

21421313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142014.

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

The square root of 21421313 is about 4628.3164325703. The cubic root of 21421313 is about 277.7252474118.

Adding to 21421313 its reverse (31312412), we get a palindrome (52733725).

The spelling of 21421313 in words is "twenty-one million, four hundred twenty-one thousand, three hundred thirteen".