21808337 has 2 divisors, whose sum is σ = 21808338. Its totient is φ = 21808336.

The previous prime is 21808321. The next prime is 21808349. The reversal of 21808337 is 73380812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19219456 + 2588881 = 4384^2 + 1609^2 .

It is a cyclic number.

It is not a de Polignac number, because 21808337 - 2⁴ = 21808321 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21808307) 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 as a sum of consecutive naturals, namely, 10904168 + 10904169.

It is an arithmetic number, because the mean of its divisors is an integer number (10904169).

Almost surely, 2^21808337 is an apocalyptic number.

It is an amenable number.

21808337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21808337 is an equidigital number, since it uses as much as digits as its factorization.

21808337 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 21808337 is about 4669.9397212384. The cubic root of 21808337 is about 279.3878505901.

The spelling of 21808337 in words is "twenty-one million, eight hundred eight thousand, three hundred thirty-seven".