21223009 has 2 divisors, whose sum is σ = 21223010. Its totient is φ = 21223008.

The previous prime is 21222979. The next prime is 21223051. The reversal of 21223009 is 90032212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20223009 + 1000000 = 4497^2 + 1000^2 .

It is a cyclic number.

It is not a de Polignac number, because 21223009 - 2⁵ = 21222977 is a prime.

It is a super-3 number, since 3×21223009³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21223409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611504 + 10611505.

It is an arithmetic number, because the mean of its divisors is an integer number (10611505).

Almost surely, 2^21223009 is an apocalyptic number.

It is an amenable number.

21223009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21223009 is an equidigital number, since it uses as much as digits as its factorization.

21223009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21223009 is about 4606.8437134333. The cubic root of 21223009 is about 276.8655918447.

The spelling of 21223009 in words is "twenty-one million, two hundred twenty-three thousand, nine".