18111641821 has 64 divisors (see below), whose sum is σ = 23455054336. Its totient is φ = 13604889600.

The previous prime is 18111641809. The next prime is 18111641843. The reversal of 18111641821 is 12814611181.

It is a happy number.

It is a 12-Lehmer number, since φ(18111641821) divides (18111641821-1)¹².

It is a cyclic number.

It is not a de Polignac number, because 18111641821 - 2¹¹ = 18111639773 is a prime.

It is the 134580-th Hogben number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18111641851) by changing a digit.

It is a nontrivial repunit in base 134579.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 33477811 + ... + 33478351.

It is an arithmetic number, because the mean of its divisors is an integer number (366485224).

Almost surely, 2^18111641821 is an apocalyptic number.

It is an amenable number.

18111641821 is a deficient number, since it is larger than the sum of its proper divisors (5343412515).

18111641821 is a wasteful number, since it uses less digits than its factorization.

18111641821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 822.

The product of its digits is 3072, while the sum is 34.

The spelling of 18111641821 in words is "eighteen billion, one hundred eleven million, six hundred forty-one thousand, eight hundred twenty-one".