21242243 has 4 divisors (see below), whose sum is σ = 23173368. Its totient is φ = 19311120.

The previous prime is 21242237. The next prime is 21242339. The reversal of 21242243 is 34224212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21242243 is a prime.

It is a super-4 number, since 4×21242243⁴ (a number of 30 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21242203) 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, 965546 + ... + 965567.

It is an arithmetic number, because the mean of its divisors is an integer number (5793342).

Almost surely, 2^21242243 is an apocalyptic number.

21242243 is a deficient number, since it is larger than the sum of its proper divisors (1931125).

21242243 is a wasteful number, since it uses less digits than its factorization.

21242243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1931124.

The product of its digits is 768, while the sum is 20.

The square root of 21242243 is about 4608.9307870698. The cubic root of 21242243 is about 276.9492058896.

Adding to 21242243 its reverse (34224212), we get a palindrome (55466455).

The spelling of 21242243 in words is "twenty-one million, two hundred forty-two thousand, two hundred forty-three".