21125563111 has 4 divisors (see below), whose sum is σ = 22368243312. Its totient is φ = 19882882912.

The previous prime is 21125563093. The next prime is 21125563169. The reversal of 21125563111 is 11136552112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21125563111 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21125563111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125569111) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 621340075 + ... + 621340108.

It is an arithmetic number, because the mean of its divisors is an integer number (5592060828).

Almost surely, 2^21125563111 is an apocalyptic number.

21125563111 is a deficient number, since it is larger than the sum of its proper divisors (1242680201).

21125563111 is a wasteful number, since it uses less digits than its factorization.

21125563111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242680200.

The product of its digits is 1800, while the sum is 28.

The spelling of 21125563111 in words is "twenty-one billion, one hundred twenty-five million, five hundred sixty-three thousand, one hundred eleven".