21523343 has 4 divisors (see below), whose sum is σ = 22789440. Its totient is φ = 20257248.

The previous prime is 21523339. The next prime is 21523351. The reversal of 21523343 is 34332512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21523343 - 2² = 21523339 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 (21523543) 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 3 ways as a sum of consecutive naturals, for example, 633023 + ... + 633056.

It is an arithmetic number, because the mean of its divisors is an integer number (5697360).

Almost surely, 2^21523343 is an apocalyptic number.

21523343 is a deficient number, since it is larger than the sum of its proper divisors (1266097).

21523343 is a wasteful number, since it uses less digits than its factorization.

21523343 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1266096.

The product of its digits is 2160, while the sum is 23.

The square root of 21523343 is about 4639.3257053154. The cubic root of 21523343 is about 278.1654855511.

Adding to 21523343 its reverse (34332512), we get a palindrome (55855855).

The spelling of 21523343 in words is "twenty-one million, five hundred twenty-three thousand, three hundred forty-three".