1243111905 has 24 divisors (see below), whose sum is σ = 2462546112. Its totient is φ = 568279584.

The previous prime is 1243111871. The next prime is 1243111931. The reversal of 1243111905 is 5091113421.

It is a happy number.

It is not a de Polignac number, because 1243111905 - 2⁷ = 1243111777 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1972879 + ... + 1973508.

It is an arithmetic number, because the mean of its divisors is an integer number (102606088).

Almost surely, 2^1243111905 is an apocalyptic number.

1243111905 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1243111905 is a deficient number, since it is larger than the sum of its proper divisors (1219434207).

1243111905 is a wasteful number, since it uses less digits than its factorization.

1243111905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3946405 (or 3946402 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 1243111905 is about 35257.7921174880. The cubic root of 1243111905 is about 1075.2350392866.

It can be divided in two parts, 12431 and 11905, that added together give a square (24336 = 156²).

The spelling of 1243111905 in words is "one billion, two hundred forty-three million, one hundred eleven thousand, nine hundred five".