21037 has 4 divisors (see below), whose sum is σ = 21340. Its totient is φ = 20736.

The previous prime is 21031. The next prime is 21059. The reversal of 21037 is 73012.

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 can be written as a sum of positive squares in 2 ways, for example, as 9801 + 11236 = 99^2 + 106^2 .

It is a 4-Lehmer number, since φ(21037) divides (21037-1)⁴.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21037 is a prime.

It is an Ulam number.

It is a Duffinian number.

21037 is a modest number, since divided by 37 gives 21 as remainder.

It is a nialpdrome in base 13.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21037.

It is not an unprimeable number, because it can be changed into a prime (21031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13 + ... + 205.

It is an arithmetic number, because the mean of its divisors is an integer number (5335).

2²¹⁰³⁷ is an apocalyptic number.

It is an amenable number.

21037 is a deficient number, since it is larger than the sum of its proper divisors (303).

21037 is a wasteful number, since it uses less digits than its factorization.

21037 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302.

The product of its (nonzero) digits is 42, while the sum is 13.

The square root of 21037 is about 145.0413734077. The cubic root of 21037 is about 27.6054354624.

Adding to 21037 its reverse (73012), we get a palindrome (94049).

The spelling of 21037 in words is "twenty-one thousand, thirty-seven".