21630337 has 2 divisors, whose sum is σ = 21630338. Its totient is φ = 21630336.

The previous prime is 21630289. The next prime is 21630353. The reversal of 21630337 is 73303612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20939776 + 690561 = 4576^2 + 831^2 .

It is a cyclic number.

It is not a de Polignac number, because 21630337 - 2⁷ = 21630209 is a prime.

It is not a weakly prime, because it can be changed into another prime (21634337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10815168 + 10815169.

It is an arithmetic number, because the mean of its divisors is an integer number (10815169).

Almost surely, 2^21630337 is an apocalyptic number.

It is an amenable number.

21630337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21630337 is an equidigital number, since it uses as much as digits as its factorization.

21630337 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 25.

The square root of 21630337 is about 4650.8426118285. The cubic root of 21630337 is about 278.6256503953.

Adding to 21630337 its reverse (73303612), we get a palindrome (94933949).

The spelling of 21630337 in words is "twenty-one million, six hundred thirty thousand, three hundred thirty-seven".