21050237 has 4 divisors (see below), whose sum is σ = 22669500. Its totient is φ = 19430976.

The previous prime is 21050231. The next prime is 21050251. The reversal of 21050237 is 73205012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6220036 + 14830201 = 2494^2 + 3851^2 .

It is a cyclic number.

It is not a de Polignac number, because 21050237 - 2⁶ = 21050173 is a prime.

It is a super-2 number, since 2×21050237² = 886224955512338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21050231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 809612 + ... + 809637.

It is an arithmetic number, because the mean of its divisors is an integer number (5667375).

Almost surely, 2^21050237 is an apocalyptic number.

It is an amenable number.

21050237 is a deficient number, since it is larger than the sum of its proper divisors (1619263).

21050237 is a wasteful number, since it uses less digits than its factorization.

21050237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1619262.

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21050237 is about 4588.0537267996. The cubic root of 21050237 is about 276.1122425572.

Adding to 21050237 its reverse (73205012), we get a palindrome (94255249).

The spelling of 21050237 in words is "twenty-one million, fifty thousand, two hundred thirty-seven".