21243371 has 4 divisors (see below), whose sum is σ = 21761544. Its totient is φ = 20725200.

The previous prime is 21243361. The next prime is 21243403. The reversal of 21243371 is 17334212.

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 21243371 - 2⁶ = 21243307 is a prime.

It is a super-2 number, since 2×21243371² = 902561622887282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21243331) 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, 259025 + ... + 259106.

It is an arithmetic number, because the mean of its divisors is an integer number (5440386).

Almost surely, 2^21243371 is an apocalyptic number.

21243371 is a deficient number, since it is larger than the sum of its proper divisors (518173).

21243371 is an equidigital number, since it uses as much as digits as its factorization.

21243371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518172.

The product of its digits is 1008, while the sum is 23.

The square root of 21243371 is about 4609.0531565605. The cubic root of 21243371 is about 276.9541079642.

Adding to 21243371 its reverse (17334212), we get a palindrome (38577583).

The spelling of 21243371 in words is "twenty-one million, two hundred forty-three thousand, three hundred seventy-one".