1243921811 has 24 divisors (see below), whose sum is σ = 1493365440. Its totient is φ = 1024650000.

The previous prime is 1243921801. The next prime is 1243921823. The reversal of 1243921811 is 1181293421.

It is a de Polignac number, because none of the positive numbers 2^k-1243921811 is a prime.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243921801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 104936 + ... + 116186.

It is an arithmetic number, because the mean of its divisors is an integer number (62223560).

Almost surely, 2^1243921811 is an apocalyptic number.

1243921811 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1243921811 is a deficient number, since it is larger than the sum of its proper divisors (249443629).

1243921811 is a wasteful number, since it uses less digits than its factorization.

1243921811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11327 (or 11304 counting only the distinct ones).

The product of its digits is 3456, while the sum is 32.

The square root of 1243921811 is about 35269.2757368223. The cubic root of 1243921811 is about 1075.4684991634.

The spelling of 1243921811 in words is "one billion, two hundred forty-three million, nine hundred twenty-one thousand, eight hundred eleven".