21291851111 has 4 divisors (see below), whose sum is σ = 22217583792. Its totient is φ = 20366118432.

The previous prime is 21291851051. The next prime is 21291851149. The reversal of 21291851111 is 11115819212.

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 21291851111 - 2³⁰ = 20218109287 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21291851171) 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, 462866306 + ... + 462866351.

It is an arithmetic number, because the mean of its divisors is an integer number (5554395948).

Almost surely, 2^21291851111 is an apocalyptic number.

21291851111 is a deficient number, since it is larger than the sum of its proper divisors (925732681).

21291851111 is an equidigital number, since it uses as much as digits as its factorization.

21291851111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 925732680.

The product of its digits is 1440, while the sum is 32.

The spelling of 21291851111 in words is "twenty-one billion, two hundred ninety-one million, eight hundred fifty-one thousand, one hundred eleven".