21007229 has 2 divisors, whose sum is σ = 21007230. Its totient is φ = 21007228.

The previous prime is 21007213. The next prime is 21007249. The reversal of 21007229 is 92270012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16605625 + 4401604 = 4075^2 + 2098^2 .

It is a cyclic number.

It is not a de Polignac number, because 21007229 - 2⁴ = 21007213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21007249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10503614 + 10503615.

It is an arithmetic number, because the mean of its divisors is an integer number (10503615).

Almost surely, 2^21007229 is an apocalyptic number.

It is an amenable number.

21007229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21007229 is an equidigital number, since it uses as much as digits as its factorization.

21007229 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 21007229 is about 4583.3643756525. The cubic root of 21007229 is about 275.9240715663.

The spelling of 21007229 in words is "twenty-one million, seven thousand, two hundred twenty-nine".