21050243 has 4 divisors (see below), whose sum is σ = 21061560. Its totient is φ = 21038928.

The previous prime is 21050231. The next prime is 21050251. The reversal of 21050243 is 34205012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21050243 - 2¹⁰ = 21049219 is a prime.

It is a super-2 number, since 2×21050243² = 886225460718098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21050203) 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, 2138 + ... + 6831.

It is an arithmetic number, because the mean of its divisors is an integer number (5265390).

Almost surely, 2^21050243 is an apocalyptic number.

21050243 is a deficient number, since it is larger than the sum of its proper divisors (11317).

21050243 is an equidigital number, since it uses as much as digits as its factorization.

21050243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11316.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21050243 is about 4588.0543806716. The cubic root of 21050243 is about 276.1122687909.

Adding to 21050243 its reverse (34205012), we get a palindrome (55255255).

The spelling of 21050243 in words is "twenty-one million, fifty thousand, two hundred forty-three".