21053243 has 8 divisors (see below), whose sum is σ = 21590928. Its totient is φ = 20520864.

The previous prime is 21053203. The next prime is 21053267. The reversal of 21053243 is 34235012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21053243 - 2¹⁰ = 21052219 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21053203) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7421 + ... + 9857.

It is an arithmetic number, because the mean of its divisors is an integer number (2698866).

Almost surely, 2^21053243 is an apocalyptic number.

21053243 is a deficient number, since it is larger than the sum of its proper divisors (537685).

21053243 is a wasteful number, since it uses less digits than its factorization.

21053243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2653.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21053243 is about 4588.3813049920. The cubic root of 21053243 is about 276.1253849888.

Adding to 21053243 its reverse (34235012), we get a palindrome (55288255).

The spelling of 21053243 in words is "twenty-one million, fifty-three thousand, two hundred forty-three".