21343421 has 8 divisors (see below), whose sum is σ = 23515488. Its totient is φ = 19210000.

The previous prime is 21343373. The next prime is 21343429. The reversal of 21343421 is 12434312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21343421 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 = 21343393 and 21343402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21343429) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8495 + ... + 10716.

It is an arithmetic number, because the mean of its divisors is an integer number (2939436).

Almost surely, 2^21343421 is an apocalyptic number.

It is an amenable number.

21343421 is a deficient number, since it is larger than the sum of its proper divisors (2172067).

21343421 is a wasteful number, since it uses less digits than its factorization.

21343421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19323.

The product of its digits is 576, while the sum is 20.

The square root of 21343421 is about 4619.8940464041. The cubic root of 21343421 is about 277.3882178356.

Adding to 21343421 its reverse (12434312), we get a palindrome (33777733).

It can be divided in two parts, 2134 and 3421, that added together give a palindrome (5555).

The spelling of 21343421 in words is "twenty-one million, three hundred forty-three thousand, four hundred twenty-one".