11811543821 has 32 divisors (see below), whose sum is σ = 15194898432. Its totient is φ = 8914844160.

The previous prime is 11811543797. The next prime is 11811543823. The reversal of 11811543821 is 12834511811.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11811543821 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11811543823) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 334220 + ... + 367866.

It is an arithmetic number, because the mean of its divisors is an integer number (474840576).

Almost surely, 2^11811543821 is an apocalyptic number.

11811543821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11811543821 is a deficient number, since it is larger than the sum of its proper divisors (3383354611).

11811543821 is a wasteful number, since it uses less digits than its factorization.

11811543821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33809.

The product of its digits is 7680, while the sum is 35.

The spelling of 11811543821 in words is "eleven billion, eight hundred eleven million, five hundred forty-three thousand, eight hundred twenty-one".