21242311 has 4 divisors (see below), whose sum is σ = 21337792. Its totient is φ = 21146832.

The previous prime is 21242237. The next prime is 21242339. The reversal of 21242311 is 11324212.

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 21242311 - 2⁹ = 21241799 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 (21240311) 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, 47406 + ... + 47851.

It is an arithmetic number, because the mean of its divisors is an integer number (5334448).

Almost surely, 2^21242311 is an apocalyptic number.

21242311 is a deficient number, since it is larger than the sum of its proper divisors (95481).

21242311 is an equidigital number, since it uses as much as digits as its factorization.

21242311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95480.

The product of its digits is 96, while the sum is 16.

The square root of 21242311 is about 4608.9381640460. The cubic root of 21242311 is about 276.9495014097.

Adding to 21242311 its reverse (11324212), we get a palindrome (32566523).

The spelling of 21242311 in words is "twenty-one million, two hundred forty-two thousand, three hundred eleven".