22240721 has 2 divisors, whose sum is σ = 22240722. Its totient is φ = 22240720.

The previous prime is 22240711. The next prime is 22240739. The reversal of 22240721 is 12704222.

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., 21492496 + 748225 = 4636^2 + 865^2 .

It is a cyclic number.

It is not a de Polignac number, because 22240721 - 2⁶ = 22240657 is a prime.

It is a Chen prime.

It is equal to p_1403381 and since 22240721 and 1403381 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 22240693 and 22240702.

It is not a weakly prime, because it can be changed into another prime (22240711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11120360 + 11120361.

It is an arithmetic number, because the mean of its divisors is an integer number (11120361).

Almost surely, 2^22240721 is an apocalyptic number.

It is an amenable number.

22240721 is a deficient number, since it is larger than the sum of its proper divisors (1).

22240721 is an equidigital number, since it uses as much as digits as its factorization.

22240721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 20.

The square root of 22240721 is about 4716.0068914284. The cubic root of 22240721 is about 281.2222124975. Note that the first 4 decimals are identical.

Adding to 22240721 its reverse (12704222), we get a palindrome (34944943).

The spelling of 22240721 in words is "twenty-two million, two hundred forty thousand, seven hundred twenty-one".