1243644263 has 4 divisors (see below), whose sum is σ = 1245287880. Its totient is φ = 1242000648.

The previous prime is 1243644251. The next prime is 1243644277. The reversal of 1243644263 is 3624463421.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1243644263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243244263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 820673 + ... + 822186.

It is an arithmetic number, because the mean of its divisors is an integer number (311321970).

Almost surely, 2^1243644263 is an apocalyptic number.

1243644263 is a deficient number, since it is larger than the sum of its proper divisors (1643617).

1243644263 is an equidigital number, since it uses as much as digits as its factorization.

1243644263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1643616.

The product of its digits is 82944, while the sum is 35.

The square root of 1243644263 is about 35265.3408178625. The cubic root of 1243644263 is about 1075.3885058360.

The spelling of 1243644263 in words is "one billion, two hundred forty-three million, six hundred forty-four thousand, two hundred sixty-three".