21243461 has 4 divisors (see below), whose sum is σ = 21278400. Its totient is φ = 21208524.

The previous prime is 21243437. The next prime is 21243473. The reversal of 21243461 is 16434212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21243461 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243361) 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, 16541 + ... + 17778.

It is an arithmetic number, because the mean of its divisors is an integer number (5319600).

Almost surely, 2^21243461 is an apocalyptic number.

It is an amenable number.

21243461 is a deficient number, since it is larger than the sum of its proper divisors (34939).

21243461 is an equidigital number, since it uses as much as digits as its factorization.

21243461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34938.

The product of its digits is 1152, while the sum is 23.

The square root of 21243461 is about 4609.0629199437. The cubic root of 21243461 is about 276.9544990796.

Adding to 21243461 its reverse (16434212), we get a palindrome (37677673).

Subtracting from 21243461 its reverse (16434212), we obtain a square (4809249 = 2193²).

The spelling of 21243461 in words is "twenty-one million, two hundred forty-three thousand, four hundred sixty-one".