21390343 has 8 divisors (see below), whose sum is σ = 23274608. Its totient is φ = 19540224.

The previous prime is 21390337. The next prime is 21390377. The reversal of 21390343 is 34309312.

It is a happy number.

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 21390343 - 2⁹ = 21389831 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 (21390043) 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, 7221 + ... + 9742.

It is an arithmetic number, because the mean of its divisors is an integer number (2909326).

Almost surely, 2^21390343 is an apocalyptic number.

21390343 is a deficient number, since it is larger than the sum of its proper divisors (1884265).

21390343 is a wasteful number, since it uses less digits than its factorization.

21390343 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17073.

The product of its (nonzero) digits is 1944, while the sum is 25.

The square root of 21390343 is about 4624.9695134130. The cubic root of 21390343 is about 277.5913418431.

Adding to 21390343 its reverse (34309312), we get a palindrome (55699655).

The spelling of 21390343 in words is "twenty-one million, three hundred ninety thousand, three hundred forty-three".