22781221 has 2 divisors, whose sum is σ = 22781222. Its totient is φ = 22781220.

The previous prime is 22781197. The next prime is 22781261. The reversal of 22781221 is 12218722.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22372900 + 408321 = 4730^2 + 639^2 .

It is a cyclic number.

It is not a de Polignac number, because 22781221 - 2⁵ = 22781189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (22781261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11390610 + 11390611.

It is an arithmetic number, because the mean of its divisors is an integer number (11390611).

Almost surely, 2^22781221 is an apocalyptic number.

It is an amenable number.

22781221 is a deficient number, since it is larger than the sum of its proper divisors (1).

22781221 is an equidigital number, since it uses as much as digits as its factorization.

22781221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 896, while the sum is 25.

The square root of 22781221 is about 4772.9677350680. The cubic root of 22781221 is about 283.4821159375.

Adding to 22781221 its reverse (12218722), we get a palindrome (34999943).

The spelling of 22781221 in words is "twenty-two million, seven hundred eighty-one thousand, two hundred twenty-one".