1243553221 has 2 divisors, whose sum is σ = 1243553222. Its totient is φ = 1243553220.

The previous prime is 1243553209. The next prime is 1243553273. The reversal of 1243553221 is 1223553421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1050732225 + 192820996 = 32415^2 + 13886^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243553221 - 2¹³ = 1243545029 is a prime.

It is a super-2 number, since 2×1243553221² = 3092849226918949682, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1243553221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1243559221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621776610 + 621776611.

It is an arithmetic number, because the mean of its divisors is an integer number (621776611).

Almost surely, 2^1243553221 is an apocalyptic number.

It is an amenable number.

1243553221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243553221 is an equidigital number, since it uses as much as digits as its factorization.

1243553221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 28.

The square root of 1243553221 is about 35264.0499801143. The cubic root of 1243553221 is about 1075.3622636293.

It can be divided in two parts, 12435 and 53221, that added together give a palindrome (65656).

The spelling of 1243553221 in words is "one billion, two hundred forty-three million, five hundred fifty-three thousand, two hundred twenty-one".