21354243 has 4 divisors (see below), whose sum is σ = 28472328. Its totient is φ = 14236160.

The previous prime is 21354241. The next prime is 21354247. The reversal of 21354243 is 34245312.

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 21354243 - 2¹ = 21354241 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21354241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3559038 + ... + 3559043.

It is an arithmetic number, because the mean of its divisors is an integer number (7118082).

Almost surely, 2^21354243 is an apocalyptic number.

21354243 is a deficient number, since it is larger than the sum of its proper divisors (7118085).

21354243 is an equidigital number, since it uses as much as digits as its factorization.

21354243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7118084.

The product of its digits is 2880, while the sum is 24.

The square root of 21354243 is about 4621.0651369571. The cubic root of 21354243 is about 277.4350923592.

Adding to 21354243 its reverse (34245312), we get a palindrome (55599555).

The spelling of 21354243 in words is "twenty-one million, three hundred fifty-four thousand, two hundred forty-three".