1243645549 has 2 divisors, whose sum is σ = 1243645550. Its totient is φ = 1243645548.

The previous prime is 1243645531. The next prime is 1243645567. The reversal of 1243645549 is 9455463421.

It is a balanced prime because it is at equal distance from previous prime (1243645531) and next prime (1243645567).

It can be written as a sum of positive squares in only one way, i.e., 807128100 + 436517449 = 28410^2 + 20893^2 .

It is an emirp because it is prime and its reverse (9455463421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1243645549 - 2¹¹ = 1243643501 is a prime.

It is a super-2 number, since 2×1243645549² = 3093308503095022802, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1243645049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621822774 + 621822775.

It is an arithmetic number, because the mean of its divisors is an integer number (621822775).

Almost surely, 2^1243645549 is an apocalyptic number.

It is an amenable number.

1243645549 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243645549 is an equidigital number, since it uses as much as digits as its factorization.

1243645549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518400, while the sum is 43.

The square root of 1243645549 is about 35265.3590510575. The cubic root of 1243645549 is about 1075.3888765072.

The spelling of 1243645549 in words is "one billion, two hundred forty-three million, six hundred forty-five thousand, five hundred forty-nine".