21031337 has 4 divisors (see below), whose sum is σ = 21056196. Its totient is φ = 21006480.

The previous prime is 21031333. The next prime is 21031349. The reversal of 21031337 is 73313012.

It is a happy number.

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 6431296 + 14600041 = 2536^2 + 3821^2 .

It is a cyclic number.

It is not a de Polignac number, because 21031337 - 2² = 21031333 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21031333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11114 + ... + 12867.

It is an arithmetic number, because the mean of its divisors is an integer number (5264049).

Almost surely, 2^21031337 is an apocalyptic number.

It is an amenable number.

21031337 is a deficient number, since it is larger than the sum of its proper divisors (24859).

21031337 is an equidigital number, since it uses as much as digits as its factorization.

21031337 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24858.

The product of its (nonzero) digits is 378, while the sum is 20.

The square root of 21031337 is about 4585.9935673745. The cubic root of 21031337 is about 276.0295818254.

Adding to 21031337 its reverse (73313012), we get a palindrome (94344349).

The spelling of 21031337 in words is "twenty-one million, thirty-one thousand, three hundred thirty-seven".