21907229 has 2 divisors, whose sum is σ = 21907230. Its totient is φ = 21907228.

The previous prime is 21907189. The next prime is 21907279. The reversal of 21907229 is 92270912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21141604 + 765625 = 4598^2 + 875^2 .

It is a cyclic number.

It is not a de Polignac number, because 21907229 - 2¹⁶ = 21841693 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21907195 and 21907204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21907279) 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 as a sum of consecutive naturals, namely, 10953614 + 10953615.

It is an arithmetic number, because the mean of its divisors is an integer number (10953615).

Almost surely, 2^21907229 is an apocalyptic number.

It is an amenable number.

21907229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21907229 is an equidigital number, since it uses as much as digits as its factorization.

21907229 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 21907229 is about 4680.5158903694. The cubic root of 21907229 is about 279.8095175541.

The spelling of 21907229 in words is "twenty-one million, nine hundred seven thousand, two hundred twenty-nine".