18661956211 has 4 divisors (see below), whose sum is σ = 18804414024. Its totient is φ = 18519498400.

The previous prime is 18661956139. The next prime is 18661956241. The reversal of 18661956211 is 11265916681.

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

It is a cyclic number.

It is not a de Polignac number, because 18661956211 - 2⁹ = 18661955699 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18661956241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71228710 + ... + 71228971.

It is an arithmetic number, because the mean of its divisors is an integer number (4701103506).

Almost surely, 2^18661956211 is an apocalyptic number.

18661956211 is a deficient number, since it is larger than the sum of its proper divisors (142457813).

18661956211 is a wasteful number, since it uses less digits than its factorization.

18661956211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142457812.

The product of its digits is 155520, while the sum is 46.

The spelling of 18661956211 in words is "eighteen billion, six hundred sixty-one million, nine hundred fifty-six thousand, two hundred eleven".